In a photo electric experiment when light of intensity I and wavelength λ is used, saturated current is found to be 10 mA. In the same experimental set up, when light of intensity I and wavelength λ / 2 is used, saturation current is found to be i. Then
A proton and an α –particle are accelerated from rest to the same energy. The de Broglie wavelengths λ p and λ α are in the ratio,
In an experiment of photoelectric effect the stopping potential was measured to be V 1 a n d V 2 with incident light of wavelength λ and λ / 2 , respectively. The relation between V 1 a n d V 2 is :
An electron is in an excited state in a hydrogen like atom. It has a total energy of -3.4 eV. The kinetic energy of electron is E and its de Broglie wavelength is λ
Work function of lithium and copper are respectively 2.3 eV and 4.0 eV. Which metal will be useful for the photoelectric cell working with visible light? ( h = 6.6 × 10 − 34 Js , c = 3 × 10 8 m / s
The frequency of incident light falling on a photosensitive metal plate is doubled, the KE of the emitted photoelectrons is
If a photocell is illuminated with a radiation of 1240 Å , then stopping potential is found to be 8 V. The work function of the emitter and the threshold wavelength are
The energy that should be added to an electron, to reduce its deBroglie wavelength from 2 × 10 − 9 m to 0.5 × 10 − 9 m will be (in eV) ( h = 6.6 × 10 − 34 Js , m e = 9 × 10 − 31 kg )
If the wavelength of the incident radiation changes from λ 1 t o λ 2 , then the maximum kinetic energy of the emitted photo electrons changes from K 1 t o K 2 ,then the work function of the emitter surface is
The resolving power of an electron microscope operated at 16 kV is R. The resolving power of the electron microscope when operated at 4 kV is
The potential energy of a particle of mass m is given by U ( x ) = E 0 ; 0 ≤ x ≤ 1 0 ; x > 1 . λ 1 and λ 2 are the de Broglie wavelengths of the particle, when 0 ≤ x ≤ 1 and x > 1 respectively. If the total energy of particle is 2E 0 ,the ratio λ 1 λ 2 will be
Silver has a work function of 4.7 eV. When ultraviolet light of wavelength 100 nm is incident upon it, a potential of 7.7 V is required to stop the photoelectrons from reaching the collector plate. How much potential will be required to stop the photoelectrons when light of wavelength 200 nm is incident upon silver?
If 10000 V is applied across an X-ray tube, what will be the ratio of de Broglie wave length of the incident electrons to the shortest wavelength of X-ray produced ( e m for electron is 1.8 × 10 11 C kg − 1 )
A material particle with a rest mass m 0 is moving with a velocity of light c. Then, the wavelength of the de Broglie wave associated with it is
What is the de Broglie wavelength of the wave associated with an electron that has been accelerated through a potential difference of 50.0 V?
A moving particle of mass m has a de Broglie wave length λ . Then energy of the particle is
Light of wavelength 1824 Å , incident on the surface of a metal, produces photo-electrons with maximum energy 5.3 eV. When light of wavelength 1216 Å is used, the maximum energy of photoelectrons is 8.7 eV. The work function of the metal surface is (approximately) in eV. (use hc = 12400 eV Å )
The energy that wold be changed of an electron to reduce its De broglie wavelength from 10 − 10 m to 0.5 × 10 − 10 m will be :
Light with an energy flux of 25 x 10 4 W m – 2 falls on a perfectly reflecting surface at normal incidence. If the surface area is 15 cm 2 , the average force exerted on the surface is
All electrons ejected from a surface by incident light of wavelength 200nm can be stopped before travelling 1m in the direction of uniform electric field of 4N/C. The work function of the surface is
When a metallic surface is illuminated with radiation of wavelength λ the stopping potential is v . If the same surface is illuminated with radiation of wavelength 2 λ the stopping potential is V 4 , The threshold wavelength for the metallic surface is
If the kinetic energy of the particle is increased to 16 times its previous vlaue, the percentage change in the de Broglie wavelength of the particle is
When the energy of the incident radiation is increased by 20%, the kinetic energy of the photoelectrons emitted from a metal surface increased from 0.5 eV to 0.8 eV. The work function of the metal is
The ratio of de-Broglie wavelengths of molecules of hydrogen and helium which are at temperature 27 o C and 127 o C respectively is x y . Find x+y
Light from a hydrogen discharge tube is incident on the cathode of a photoelectric cell the work function of the cathode surface is 3.4 eV. In order to reduce the photo-current to zero the voltage of the anode relative to the cathode must be made
The wavelength λ e of an electron and λ p of a photon of same energy E are related by
A certain metallic surface is illuminated with monochromatic light of wavelength, λ . The stopping potential for photoelectric current for this light is 3 V 0 . If the same surface is illuminated with light of wavelength 2 λ , the stopping potential is V 0 . The threshold wavelength for this surface for photo-electric effect is
The de-Broglie wavelength of neutrons in thermal equilibrium at temperature T is
A and B are two photosensitive materials have their work functions are W and 2W. Light of same frequency and intensity falling on both the materials. If the maximum kinetic energy of the photo electrons are in the ratio 3:1 then the maximum kinetic energy of the electrons from A is
Radiation pressure on any surface is:
A metallic surface is illuminated with monochromatic light of wavelength λ and stopping potential for photoelectric current is 5 v o when the same metallic surface is illuminated with a light of wavelength 2 λ , the stopping potential is V o . What is the threshold wavelength for the surface ?
At what rate should light energy be allowed to fall normally on a perfectly reflecting mirror with 1 c m 2 of area for one hour such that the force that acts on the mirror is 6.7 × 10 − 8 N ?
Light of wavelength 2475 A 0 is incident on Barium. Photoelectrons emitted describe a circle of radius 100 cm by a magnetic field of flux density 1 17 × 10 − 5 Tesla. The workfunction of Barium is (Given e m = 1.7 × 10 11 C/Kg)
10 – 3 walt of 5000 A o light is directed on a photoelectric cell. If the current in the cell is 0.16 μ A , the percentage of incident photons which produce photo electrons, is
If de broglie wavelength of electron in the ground state of hydrogen atom is λ , what is the de Broglie wavelength of electron in the first excited state of H e + i o n ?
5 volt of stopping potential is needed for the photo electrons emitted out of a surface of work function 2.2 eV by the radiation of wavelength
When photon of energy 4.0 eV strikes the surface of a metal A, the ejected photoelectrons have maximum kinetic energy T A e V and de-Broglie wavelength λ A . The maximum kinetic energy of photoelectrons liberated from another metal B by photon of energy 4.50 eV is T B = T A − 1.5 e V . If the de-Broglie wavelength of these photoelectrons λ B = 2 λ A , then the work function of metal B is:
In a photo electric cell, the wavelength of incident light is changed from 4000 A o t o 3600 A o . Then the change in stopping potential will be
In a photo electric experiment, work function of a target metal is 1ev and wavelength of light used in the experiment is 3000 A o Then stopping potential will be
Consider two light sources of wavelength λ 1 and λ 2 λ 1 > λ 2 which are emitting n 1 and n 2 photons respectively, in a given time. Assume equal power for both the sources, then
When radiation of wavelength λ is used to illuminate a metallic surface, the stopping potential is V. When the same surface is illuminated with radiation of wavelength 3 λ , the stopping potential is V 4 . If the threshold wavelength for the metallic surface is n λ ,then value of n will be
The surface of a metal is illuminated alternately with photons of energies E 1 = 4 eV and E 2 = 2.5 eV respectively. The ratio of maximum speeds of the photoelectrons emitted in the two cases is 2. The work function of the metal in (eV) is .
When stopping potential is applied in an experiment of photoelectric effect, no photocurrent is observed. This means that
Mark the incorrect one.
While studying, effect of variation of intensity on the photocurrent, intensity of light is changed in a photocell by
A photo cell is illuminated by a small bright source placed one metre away.When the same source of light is placed two metres away, the electron emitted by the photo cathode
Variation of photoelectric current with intensity of light is
When orange light falls on a photo sensitive surfaces the photo current begins to flow. The velocity of emitted electrons will be more when surface is hit by
de–Broglie hypothesis is a conclusion drawn from
The wavelength of matter waves does not depend on
Einstein’s picture of photoelectric effect was accepted using
In the experimental arrangement to study variation of photocurrent, the frequency of light is changed by
The number of electrons emitted by a surface exposed to light is directly proportional to
De Broglie suggested that the elementary particles like electrons, protons and neutrons will exhibit
When the intensity of light is increased
The slope of the graph drawn between stopping potential and frequency of incident radiation will be
Davisson – Germer experiment confirms de – Broglie relation by
Davison and Germer's and G.P. Thomson's experiments gives
When a source of light is kept at 0.5m from a photo cell, the cut off voltage is found to the V 0 . If the distance of the source is doubled the cut off voltage will be
In Davission experiment, if applied accelerating voltage is increased. The diffracted electron beam will have the maximum at a value of θ that
Consider the two following statements A and B and identify the correct choice given in the answers. A) In photo voltaic cells photo electric current produced is not proportional to the intensity of incident light. B) In gas filled photoemissive cells, the velocity of photo electrons depends on the wave length of the incident radiation
The threshold wavelength for photoelectric emission from a metal is 5,200A 0 . Photo-electrons will be emitted when this metal is illuminated with monochromatic radiations from a) 5.0 watt infrared lamp b) 1 watt infrared lamp c) 50 watt ultra violet lamp d) 1 watt ultraviolet lamp
Consider the following statements A) Saturation photocurrent increases with increase of intensity of light B) The maximum kinetic energy of the photo electron increases with increase of intensity of light
Light of wavelength 2475 A is incident on barium. Photoelectrons emitted describe a circle of radius 100 cm by a magnetic field of flux density 1 17 × 10 − 5 Tesla. Work function of the barium is (Given e m = 1 .7 × 10 11 )
Five elements A, B, C, D and E have work functions 1.2 eV, 2.4 eV, 3.6 eV, 4.g eV and 6 eV respectively. If light of wavelength 4000 A o is allowed to fall on these elements, then photoelectrons are emitted by
Two large parallel plates are connected with the terminal of 100 V power supply. These plates have a fine hole at the centre. An electron having energy 200 eV is so directed that it passes through the holes. When it comes out its de-Broglie wavelength is
In a photoemissive cell with executing wavelength λ , the fastest electron has speed v. If the exciting wavelength is changed to 3 λ /4, the speed of the fastest emitted electron will be
A photon and an electron have equal energy E. λ photon / λ electron is proportional to
Photoelectric emission is observed from a metallic surface for frequencies ν 1 and ν 2 of the incident light rays ( ν 1 > ν 2 ). If the maximum values of kinetic energy of the photoelectrons emitted in the two cases are in the ratio of I : k, then the threshold frequency of the metallic surface is
Work function of lithium and copper are respectively 2.3 eV and 4.0 eV. Which one of the metal will be useful for the photoelectric cell working with visible light? h = 6 .6 × 10 − 34 J − s , c = 3 × 10 8 m / s
Light from a hydrogen discharge tube is incident on the cathode of a photoelectric cell the work function of the cathode surface is 4.2 eV. In order to reduce the photocurrent to zero the voltage of the anode relative to the cathode must be made
A silver ball of radius 4.8 cm is suspended by a thread in the vacuum chamber. UV light of wavelength 200 nm is incident on the ball for some times during which a total energy of 1 × 10 − 7 J falls on the surface. Assuming on an average one out of 10 3 photons incident is able to eject electron. The potential on sphere will be
The ratio of de-Brogiie wavelengths of molecules of hydrogen and helium which are at temperature 27°C and 127°C respectivell is
In a photocell bichromatic light of wavelength 2475 A o and 6000 A o are incident on cathode whose work function is 4.8 eV. If a uniform magnetic field of 3 x 10 – 5 Tesla exists parallel to the plate, the radius of the path describe by the photoelectron will be (mass of electron = 9 x 10 – 31 kg)
The value of stopping potential in the following diagram
In the following diagram if V 2 > V 1 then
Energy of a photon is E r for red light, E v for violet light, E g for green light and E b for blue light. Then
What will be the de Broglie wavelength of the electron in the first excited state of H e + ion?
The circumference of the second Bohr orbit of electron in hydrogen atom is 600 nm. The potential difference that must be applied between the plates so that the electrons have the de Broglie wavelength corresponding in this circumference is
An electron and a photon have same wavelength. If p is the momentum of electron and E the energy of photon, the magnitude of p/E in SI unit is
The minimum intensity of light to be detected by human eye is 10 -10 W/m 2 . The number of photons of wavelength 5.6 x 10 -7 m entering the eye, with pupil area 10 -6 m 2 ,per second for vision will be nearly
An electron is accelerated through a potential difference of V volt. It has a wavelength λ associated with it. Through what potential difference an electron must be accelerated so that its de Broglie wavelength is the same as that of a proton? Take mass of proton to be 1837 times larger than the mass of electron.
Radiation pressure on any surface
The number of photons ( λ = 6630 Å ) that strike per second on a totally reflecting screen (as shown in figure), so that a force of 1N is exerted on the screen, is approximately
In the experiment on photoelectric effect, the graph between E K(max) and v is found to be a straight line as shown in figure. The threshold frequency and Planck’s constant according to this graph are
A photosensitive material is at 9 m to the left of the origin and the source of light is at 7 m to the right of the origin along x-axis. The photosensitive material and the source of light start from rest and move, respectively, with 8 i ^ m s -1 and 4 i ^ ms -1 . The ratio of intensities at t=0 to t=3 s as received by the photosensitive material is
In a photocell, with excitation wavelength λ , the faster electron has speed v. If the excitation wavelength is changed to 3 λ / 4 , the speed of the fastest electron will be
A silver ball of radius 4.8 cm is suspended by a thread in the vacuum chamber. UV light of wavelength 200 nm is incident on the ball for some times during which a total energy of 1 x 10 -7 J falls on the surface. Assuming on an average one out of 10 3 photons incident is able to eject electron, The potential on sphere will be
In a photo-emissive cell, with exciting wavelength λ , the maximum kinetic energy of the electron is K. If the exciting wavelength is changed to 3 λ /4, the kinetic energy of the fastest emitted electron will be
Neutrons in thermal equilibrium with matter at 27 o C can be thought to behave like ideal gas. Assuming them to have a speed of v rms , If the de-Broglie wavelength λ is 11 N 156 nm . The value of N is [Take m n = 1.69 × 10 − 27 kg , k = 1.44 × 10 − 23 J / K , h = 6.60 × 10 − 34 Jsec
What will be the ratio of de-Broglie wavelengths of proton and α -particle of same energy?
The de-Broglie wavelength of an electron moving with a velocity 1.5 x 10 8 ms -1 is equal to that of a photon. The ratio of the kinetic energy of the electron to that of the photon is .
de Broglie wavelength of a particle moving with kinetic energy 2 MeV is 100 A o . What is the de Broglie wavelength of a particle moving with kinetic energy 32 MeV?
In a photo electric experiment, the metal surface is illuminated by a beam of light of intensity I and frequency ν . Maximum kinetic energy of photo electron is found to be K m . Keeping the intensity unchanged, if another light of frequency ν /2 is used in the same experimental set up, then saturated photo current
A 60 W bulb is place d at a distance of 4 m from you. The bulb is emitting light of wavelength 600 nm uniformly in all directions. In 0.1 s, how many photons enter your eye if the pupil of the eye is having a diameter of 2 mm? [Take hc = 1240 eV-nm]
What is the lowest frequency of light (in x 10 14 Hz) that will cause the emission of photoelectrons from the surface of a metal (for which work function is 1.65 eV)?
According to de-Broglie, the de-Broglie wavelength for electron in an orbit of hydrogen atom is 10 -9 m. What is the principal quantum number for this electron?
A totally reflecting, small plane mirror placed horizontally faces a parallel beam of light as shown in the figure. The mass of the mirror is 20 g. Assume that there is no absorption in the lens and that 30% of the light emitted by the source goes through the lens. The power of the source (in MW) needed to support the weight of the mirror is
With what velocity (in m/s) must an electron travel so that its momentum is equal to that of photon with a wavelength of λ = 5200 Å
In a photoelectric experiment for 4000 A° incident radiation, the potential difference to stop the ejection is 2 V. If the incident light is changed to 3000 A, then the potential required to stop the ejection of electron will be:
The minimum intensity of light to be detected by human eye is 10 − 10 Wm − 2 . The number of photons of wavelength 5.6 × 10 − 7 m entering the eye, with pupil area 10 − 6 m 2 , per second for vision will be nearly
Two identical metal plates show photoelectric effect by a light of wavelength λ A falling on plate A and λ B on plate B λ A = 2 λ B . The maximum kinetic energy of electrons is :
Photoelectric work function of a metal is 1 e V Light of wavelength λ =3000 Å falls on it, The photo-electrons come with velocity
If 5% of the energy supplied to a bulb is radiated as visible light, how many quanta are emitted per sec by a 100 watt lamp ? Assume wavelength of visible light as 5.6 x10 -5 cm
Given that a photon of light of wavelength 1000 Å has an energy equal to 1.23 eV. When light of wavelength 5000 Å and intensity I 0 falls on photoelectric cell, the saturation current is 0 . 40 x 10 6 amp. and the stopping potential is 1.36 V. Then the work-function is
In a photo-electric cell, the wavelength of incident light is changed from 4000 Å to 3000 Å then change in stopping potential will be
What is the stopping potential for photo electrons ejected from a metal of work-function 1.2 eV when the incident light consists of photons of energy 1.8 eV ?
A proton and an electron ate accelerated by the same potential difference.If λ e and λ p denote de Broglie wavelength of electron and proton, then
When a certain photo-sensitive surface is illuminated with monochromatic light of frequency v, the stopping potential for photo-electric current is V 0 / 2When the same surface is illuminated by mono-chromatic light of frequency v / 2, the stopping potential is V 0 . The threshold frequency for photoelectric emission is
A photon and an electron possess same de-Broglie wavelength. Given that c is speed of light and v, the speed of electrons, which of the following relations is correct ? Here E e = K.E. of electron, E ph = K.E. of photon, p e = momentum of electron, p ph = momentum of photon
Light of wavelength 180 nm ejects photoelectrons from a plate of metal whose work-function is 2 eV. If a uniform magnetic field of 5 × 10 -5 T be applied parallel to the plate, what would be the radius (in m) of the path followed by electrons ejected normally from the plate with maximum energy?
The de Broglie wavelength of the electron in the first Bohr orbit of the hydrogen atom is
From the given figure, describing photoelectric effect, which of the following can be inferred correctly?
A proton accelerated through a potential difference of 100V, has de – Brogile wavelength λ 0 . The de – Brogile wavelength of an α – particle, accelerated through 800 V is
Electrons with de-Broglie wavelength λ falls on the target in an x-ray tube. The cut- off wavelength of the emitted X-ray is
An electron of mass m with an initial velocity v = v 0 i ^ v 0 > 0 enters an electric field E = – E 0 i ^ E 0 = constant > 0 ) at t = 0 . If λ 0 is its de-Broglie wavelength initially, then its de- Broglie wavelength at time t is
When the light of frequency 2 ϑ 0 (where ϑ 0 is threshold frequency), is incident on a metal plate, the maximum velocity of electrons emitted is v 1 . When the frequency of the incident radiation is increased to 5 ϑ 0 , the maximum velocity of electrons emitted from the same plate is v 2 . The ratio of v 1 to v 2 is
An electron of mass m and a photon have same energy E . The ratio of de-Broglie wavelengths associated with them is
The radius of the second orbit of an electron in hydrogen atom is 2.116 A 0 . The de-Broglie wavelength associated with this electron in this orbit would be
A brilliant arc lamp delivers a luminous flux of 100 W to a 1 m 2 absorber. The force due to radiation pressure is
A photoelectric surface is illuminated successively by monochromatic light of wavelength λ and λ 2 . If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the first case, the work function of the surface of the material is (h = Planck’s constant, c = speed of light)
An electron is accelerated through a potential difference of 10,000 V. Its de Broglie wavelength is, (nearly) m e = 9 × 10 – 31 kg
Which of the following pair can follow Heisenberg uncertainty principle?
Light of wavelength 500 nm is incident on a metal with work function 2.28 eV. The de Broglie wavelength of the emitted electron is
Which of the following figures represent the variation of particle momentum and the associated de-Broglie wavelength?
Photons with energy 5 eV are incident on a cathode C in a photoelectric cell. The maximum energy of emitted photoelectrons is 2 eV. When photons of energy 6 eV are incident on C, no photoelectrons will reach the anode A, if the stopping potential of A relative to C is
A source of light is placed at a distance of 50 cm from a photo cell and the stopping potential is found to be V 0 . If the distance between the light source and photo cell is made 25 cm, the new stopping potential will be :
An image of sun is formed by a lens of focal length 30 cm on the metal surface of a photoelectric cell and it produces a current I. The lens forming the image is then replaced by another lens of same diameter but of focal length 15 cm. The photocurrent in this case will be : (In both case plate is kept at focal plane)
The de-Broglie wavelength of a neutron in thermal equilibrium with heavy water at a temperature T (kelvin) and mass m, is
Light with an average flux of 20 W / cm 2 falls on a non-reflecting surface at normal incidence having surface area 20 cm 2 . The energy received by the surface during time span of 1 minute is:
An electron is accelerated from rest through a potential didifference of V volt. If the de Broglie wavelength of the electron is 1 . 227 x 10 – 2 nm, the potential difference is :
Light of frequency 1.5 times the threeshold frequency is incident on a photosensitive material. What will be the photoelectric current if the frequency is halved and intensity is doubled ?
The de Broglie wavelength of an electron moving with kinetic energy of 144 eV is nearly
The wave nature of electrons was experimentally verified by,
The wrong statements among the following regarding photo electric effect–
In a photoelectric experiment, with light of wavelength λ , the fastest electron has speed v. If the exciting wavelength is changed to 3 λ 4 the speed of the fastest emitted electron will become
Light with an energy flux of 16 W / c m 2 falls on a non reflecting surface at normal incidence. If the surface has an area of 20 c m 2 , find the average force exerted on the surface during a 30 minute time span.
If the mass of neutron is 1 . 7 x 10 – 27 k g , then the de-Broglie wavelength of neutron of energy 3 eV is: ( h = 6 . 6 x 10 – 34 Js )
The maximum wave length of radiation that can produce Photoelectric effect in a certain metal is 200 nm. The maximum kinetic energy acquired by electron due to radiation of wavelength 100 nm will be
Consider an electron in the n th orbit of a Hydrogen atom in the Bohr model. The circumference of the orbit can be expressed in terms of de Broglie wavelength λ of the electron as
When a mono-chromatic point source of light is at a distance r from a photoelectric cell, the cut-off voltage is V and the saturation current is I . If the same source is placed at a distance 3r away from the photoelectric cell, then
The surface of some material is irradiated in turn, by waves of wavelength λ 1 = 6.4 × 10 − 7 m a n d λ 2 = 9.8 × 10 − 7 m respectively. The ratio of stopping potential in two cases is 2 : 1. The work function is
A particle of mass M at rest, decays into two masses m 1 a n d m 2 with non-zero velocities. The ratio of Broglie wave length of the particles ‘ λ 1 λ 2 ’ is
Ultra violet light of wavelength 66.26 nm and intensity 2 w / m 2 falls on potassium surface by which photoelectrons are ejected out. If only 0.1% of the incident photons produce photoelectrons and surface area of metal surface is 4 m 2 , how many electrons are emitted per second ?
The work function of a photosensitive material is 4.0 eV. The longest wavelength of light that can cause photon emission from the substance is (approximately)
An electron with speed V and a photon with speed C have the same de Broglie wave length. If the energy and momentum of electron are E e and P e and that of photon are E p and P p respectively, Then correct statement is
If 5% of the energy supplied to a bulb is radiated as visible light, how many quanta are emitted per second by a 100 W lamp? Assume wave length of visible light as 5 .6 × 10 − 5 cm ?
The kinetic energy of electron is E when incident light has wavelength λ . To increase the kinetic energy to 2E, the incident light must have wave length
How many photons of a radiation of wavelength λ = 5 × 10 – 7 m must fall per second on a blackened plate in order to produce a force of 6.62 × 10 – 5 N?
A particle moving in the positive X direction has de Broglie wavelength λ 1 . Another particle also moving in the same direction has de Broglie wavelength λ 2 . The two particles make a collision and after the collision they move together as a single particle. The de Broglie wavelength of this single particle is given by
A surface irradiated with light λ = 480 nm gives out electrons with maximum velocity v m/s, the cut off wavelength being 600 nm. The same surface would release electrons with maximum velocity 2v m/s if it is irradiated by light of wavelength.
A particle of mass 3m at rest decays into two particles of masses m and 2m having non-zero velocities. The ratio of the de Broglie wavelengths of the particles ( λ 1 λ 2 ) is
When a metallic surface is illuminated with monochromatic light of wavelength λ stopping potential for photoelectric current is 3 V 0 . When the same metallic surface is illuminated with a light of wavelength 2 λ the stopping potential is V 0 . The threshold wavelength for the surface is
A modern 200 watt sodium street lamp emits yellow light of wavelength 0 . 6 μ m . Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is
The lowest frequency of light that will cause the emission of photoelectrons from the surface of a metal (for which work function is 1.65 eV) will be
Electron from n = 2 to n =1 in Hydrogen atom is made to fall on a metal surface with work function 1.2 eV. The maximum velocity of photo electrons emitted is nearly equal to
Let K 1 be the maximum kinetic energy of photoelectrons emitted by light of wavelength λ 1 and k 2 corresponding to wavelength λ 2 . If λ 1 = 2 λ 2 then :
Which of the following graphs correctly represents the variation of particle momentum with associated de Broglie wavelength ?
A beam of electromagnetic radiation of intensity 6.4 × 10 − 5 W / c m 2 is comprised of wavelength, λ = 310 nm. It falls normally on a metal(work function φ = 2 e V ) of surface area 1 c m 2 . If one in 10 3 photons ejects an electron, total number of electrons ejected in 1s is 10 x (hc = 1240 eVnm, 1eV = 1 . 6 × 10 – 19 J) , then x is
An electron(of mass m) and a photon have some energy E in the range of a few eV. The ratio of the de-Broglie wavelength associated with the electron and the wavelength of the photon is (c=speed of light in vacuum)
Matter waves
Light of frequency 1.5 times the threshold frequency is incident on photo-sensitive material. If the frequency is halved and intensity is doubled, the photo current becomes
An electron (mass m) with initial velocity ν = ν 0 i ^ + ν 0 j ^ is in an electric field E = − E 0 k ^ . If λ 0 is initial de-Broglie wavelength of electron, its de-Broglie wavelength at time t is given by :
If a stationary positron and electron combine, the wavelength of resulting radiation will be m 0 = s t a t i o n a r y m a s s o f e l e c t r o n
Radiation, with wavelength 6561 A 0 falls on a metal surface to produce photoelectrons . The electrons are made to enter a uniform magnetic field of 3 × 10 − 4 T . If the radius of the largest circular path followed by the electrons is 10 mm, the work function of the metal close to:
An electron of mass m and magnitude of charge e initially at rest accelerated by a constant electric field E. The rate of change of de-Broglie wavelength of this electron at time t (ignoring relativistic effects) is:
A particle moving with kinetic energy E has de Broglie wavelength λ . If energy Δ E is added to its energy, the wavelength become λ / 2 . Value of Δ E is:
The momentum of a photon of an electro magnetic radiation radiation is 3.3 × 10 − 29 k g − m / s . What is the frequency of associated waves? ( h = 6.6 × 10 − 34 J − S and c = 3 × 10 8 m / s )
Light of wavelength λ strikes a photo electric surface and electrons are ejected with maximum kinetic energy K. If K is to be increased to twice its original value, the wavelength must be changed to λ ‘ . I f λ = 6200 A o a n d λ ‘ = 5000 A o , Then value of k is
P and Q are two points at distances 10 cm and 20 cm from the axis of a long thin straight current carrying wire. Then the ratio of magnetic energy densities at P and Q is
A particle is moving 5 times as fast as an electron. The ratio of the de-Broglie wavelength of the particle to that of the electron is 1 . 878 × 10 – 4 . The mass of the particle is close to:
The work functions for sodium and copper are 2 eV and 4 eV. Which of them is suitable for a photocell with 400 nm light?
A photon of energy ‘2’ ev is incident on a metal, The minimum de-Broglie wave length of the emitted electrons is λ . When the wave length of the incident radiation is reduced by 60% the minimum de-Broglie wave length of the emitted electrons is λ 2 The work function of the metal is
When the wavelength of radiation falling on a metal is changed from 500 nm to 200 nm, the maximum kinetic energy of the photoelectrons becomes three times larger. The work function of the metal is close to :
Two sources of light emit X – rays of wavelength 1nm and visible light of wavelength 500nm, respectively. Both the sources emit light of the same power 200W. The ratio of the number density of photons of X – rays to the number density of photons of the visible light of the given wavelength is :
Given figure shows few data points in a photo electric effect experiment for a certain metal. The minimum energy for ejection of electron from its surface is : (Planck’s constant h = 6.62 × 10 − 34 J ⋅ s )
Particle A of mass m A = m 2 moving along the x-axis with velocity v 0 collides elastically with another particle B at rest having mass m B = m 3 . If the particles move along the x-axis after the collision, the change Δ λ in de-Broglie wavelength of particle A, in terms of its de-Broglie wavelength λ 0 before collision is :
In a photoelectric effect experiment, the graph of stopping potential V versus reciprocal of wavelength obtained is shown in the figure. As the intensity of incident radiation is increased:
A beam of electrons of energy E scatters from a target having atomic spacing of 1 A 0 . The first maximum intensity occurs at θ = 60 0 . Then E i n e V is (Planck constant h = 6.64 × 10 − 34 J s , 1 e V = 1.6 × 10 − 19 J , e l e c t r o n m a s s m = 9.1 × 10 − 31 k g )
Two different monochromatic beams of same intensity hit a screen. If number of photons hitting the screen by beam A is twice than by B. Then f A : f B is
To observe the effect of intensity of light on photocurrent,
Photo electric effect supports quantum nature of light because
The best photo electric substance is
If the frequency of incident light is tripled, the stopping potential will
A non mono chromatic light is used in an experiment on photo electric effect. The stopping potential is related to the
photo electric current
It is easier to remove an electron from sodium than from copper. If ( ν 0 ) s and ( ν 0 ) c are their threshold frequencies respectively. Then
Will photo electron be emitted by a copper surface, whose threshold wave length is 2800 A 0 when illuminated by visible light ?
Intensity of light incident on a photo sensitive surface is doubled. Then
If the wave length of light in an experiment on photo electric effect is doubled keeping the intensity constant
Relation between the stopping potential Vo of a metal and the maximum velocity v of the photo electrons is
A cathode of a photo electric cell is changed such that the work function changes from W 1 to W 2 (W 1 < W 2 ) . The currents before and after changes are I 1 and I 2 all other conditions remaining un-changed, then (assuming h ν > W 2 )
A laser beam of output power ‘P’ consists only of wavelength λ . If Planck’s constant is h and the speed of light is c, then the number of photons emitted per second is
The threshold wave length of a metal for photoelectric emission is 5000 A°. Photo electric emission will take place from this surface if irradiated by radiation from
Pick the wrong statement of the following.
According to Einstein’s photoelectric equation, the plot of the KE of emitted photoelectrons from a metal and the frequency of the incident radiation, gives a straight line, whose slope
The correct curve between the stopping potential (V o ) and intensity of incident light (I) is
The threshold frequency for a metallic surface corresponds to an energy of 6.2eV and the stopping potential for a radiation incident on this surface is 5V. The incident radiation lies in
The graph of collector plate potential versus photo electric current is shown below. If ‘I’ denotes intensity of incident radiation, then
Stopping potential is more negative for
The anode voltage of a photo cell is kept fixed. The wavelength λ of the light falling on the cathode is gradually changed. The plate current I of the photo cell varies as follows
Millikan proved validity of Einstein`s photo-electric equation by
For the graph shown, if ‘f’ denotes frequency of incident light
A point source of light is used in an experiment on photoelectric effect. Which of the following curves best represnts the variation of photoelectric current ‘i’ with distance ‘d’ of the source from the emitter?
Figure represents a graph of kinetic energy K of photoelectrons and frequency ν for a metal used for cathode in photoelectric experment. The work function of metal is
The wave nature of electron was verified by
the frequency of a photonof momentum p will be
The matter waves are
The De Broglie wavelength of a particle is equal to that of a photon, then the energy of photon will be
If the value of Planck’s constant is more than its present value then the De Broglie wavelength associated with a material particle will be
Macroscopic objects like a moving cricket ball does not show any wave like properties bacause
Wave is associated with matter
de-Broglie wavelength associated with a moving ball of mass 0.12 kg and moving at a speed of 20 m/s is
A particle is moving three times as fast that of an electron. The ratio of de – Broglie wavelength of particle to that of the electron is 1.83×10 –4 . Then the particle is
A particle is dropped from a height H. The de – Broglie wavelength associated with particle is proportional to
An electron is moving with an initial velocity V = V 0 i ^ and is in a magnetic field B = B 0 j ^ . Then, its de Broglie wavelength
de Broglie hypothesis is true for
Wave nature of electrons is exploited in
In Davisson-Germer experiment, at acclerating voltage of 54 V, intensity of scattered electrons is maximum at a scattering angle of 50°. The appearance of the peak in a particular direction is due to
Pick up the correct statements of the following. a) Threshold frequency does not depends on intensity of incident light. b) Threshold frequency is different for different metals. c) The intercept on X-axis of a graph drawn between stopping potential on Y-axis and frequency on X-axis gives threshold frequency.
Statement (A) : According to wave nature of light the radiant energy spreads out continuously in the form of wave. Statement (B) : According to particle nature it behaves as a particle and is localized at a point in space.
The photoelectric threshold wavelength of a certain metal is 3000 A. If the radiation of 2000 A is incident on the metal
When yellow light is incident on a surface, no electrons are emitted while green light can emit. If red light is incident on the surface, then
Assuming photoemission to take place, the factor by which the maximum velocity of the emitted photoelectrons changes when the wavelength of the incident radiation is increased to four times. is
When a point source of light is at a distance of one metre from a photo cell, the cut off voltage is found to be V. If the same source is placed at 2 m distance from photo cell, the cut off voltage will be
A photocell stops emission if it is maintained at 2V negative potential. The energy of most energetic photoelectron is
Light of wavelength 4000 A falls on a photosensitive metal and a negative 2 V potential stops the emitted electrons. The work function of the material (in eV) is approximately h = 6 . 6 × 10 – 34 Js , e = 1 . 6 × 10 – 19 C , c = 3 × 10 8 ms – 1
If the work function of a metal is ‘Φ’ and the frequency of the incident light is ‘v’, there is no emission of photoelectron if
Light of wavelength 5000 A falls on a sensitive plate with photoelectric work function of 1.9 eV. The kinetic energy of the photoelectron emitted will be
If the work function of a photo metal is 6.825 eV . Its threshold wavelength will be c = 3 × 10 8 m / s
When light of wavelength 300 nm (nanometre) falls on a photoelectric emitter, photoelectrons are liberated. For another emitter, however light of 600 nm wavelength is sufficient for creating photoemission. What is the ratio of the work functions of the two emitters?
The frequency of the incident light falling on a photosensitive metal plate is doubled, the kinetic energy of the emitted photoelectrons is
Light of frequency 8 × 10 15 Hz is incident on a substance of photoelectric work function 6.125 eV. The maximum kinetic energy of the emitted photoelectrons is
Threshold wavelength for photoelectric effect on sodium is 5000 A. Its work function is
What is the stopping potential when the metal with work function 0.6 eV is illuminated with the light of 2 eV?
The work functions for sodium and copper are 2 eV and 4 eV. Which of them is suitable for a photocell with 4000 A light?
Light of frequency 4 v 0 is incident on the metal of the threshold frequency v 0 . The maximum kinetic energy of the emitted photoelectrons is
When radiation is incident on a photoelectron emitter, the stopping potential is found to be 9 volts. If e/m for the electron is 1 . 8 x 10 11 C kg – 1 the maximum velocity of the ejected electrons is
For intensity I of a light of wavelength 5000 A the photoelectron saturation current is 0.40 µA and stopping potential is 1.36 V, the work function of metal is
Energy required to remove an electron from aluminium surface is 4.2 eV. If light of wavelength 2000 A o falls on the surface, the velocity of the fastest electron ejected from the surface will be
Light of wavelength 1824 A o , incident on the surface of a metal, produces photo-electrons with maximum energy 5.3 eV. When light of wavelength 1216 A o is used, the maximum energy of photoelectrons is 8.7 eV. The work function of the metal surface is
Mercury violet tight λ = 4558 A o is falling on a photosensitive material (Φ = 2.5 eV). The speed of the ejected electrons is in ms -l . about
When a metal surface is illuminated by light of wavelengths 400 nm and 250 nm, the maximum velocities of the photoelectlons ejected are v and 2v respectively. The work function of the metal is (h : Planck’s constant, c : velocity of light in air)
The stopping potential as a function of the frequency of the incident radiation is plotted for two different photoelectric surfaces A and B. The graphs show that work function of A is
The figure shows the variation of photo-current with anode potential for a photo-sensitive surface for three different radiations. Let I a , I b and I c be the intensities and f a , f b and f c be the frequencies for the curves a. b and c respectively
The curves (a), (b), (c) and (d) show the variation between the applied potential difference (V) and the photoelectric current (l), at two different intensities of light ( I 1 > I 2 ) but of same frequency. In which figure is the correct variation shown?
When radiation of wavelength λ is incident on a metallic surface, the stopping potential is 4.8 volts. If the same surface is illuminated with radiation of double the wavelength, then the stopping potential becomes 1.6 volts. Then the threshold wavelength for the surface is
The work functions of metals A and B are in the ratio 1 : 2. If light of frequencies f and, 2f are incident on the surfaces of A and.B respectively, the ratio of the maximum kinetic energies of photoelectrons emitted is (f is greater than threshold frequency of A, 2f is greater than threshold frequency of B)
If light of wavelength λ 1 is allowed to fall on a metal, then kinetic energy of photoelectrons emitted is E 1 . If wavelength of light changes to λ 2 then kinetic energy of electrons changes to E 2 . Then work function of the metal is
If maximum velocity with which an electron can be emitted from a photo cell is 4 x 10 8 cm / sec, the stopping potential is (mass of electron = 9 x 10 31 kg)
The maximum velocity of electrons emitted from a metal surface is V when frequency of light failing on it is ν The maximum velocity when frequency becomes 4 ν is
A particle of mass M at rest decays into two particles of masses m 1 and m 2 having non-zero velocities. The ratio of the de-Broglie wavelengths of the particles λ 1 / λ 2 is
The collector plate in an experiment on photoelectric effect is kept vertically above the emitter plate. Light source is put on and a saturation photo current is recorded. An electric field is switched on which has a vertically downward direction. Then
In a photo electric experiment when yellow light is used stopping potential is found to be z e r o . If the yellow light is replaced by blue light, then stopping potential becomes V 0 . If red light is used in the same experiment the stopping potential would be
Ultraviolet light of wavelength 300 nm and intensity 1 . 0 watt / m 2 falls on the surface of a photosensitive material. If 1% of the incident photons produce photoelectrons, then the number of photoelectrons emitted from an area of 1 . 0 cm 2 of the surface is nearly
The largest distance between the interatomic planes of a crystal is 10 – 7 cm. The upper limit for the wavelength of X-rays which can be usefully studied with this crystal is
A photon of wavelength 6630 A o is incident on a totally reflecting surface. The momentum delivered by the photon is equal to
The ratio of de-Broglie wavelength of a α-particle to that of a proton being subjected to the same magnetic field so that the radii of their path are equal to each other assuming the field induction vector B is perpendicular to the velocity vectors of the α-particle and the proton ts
When a proton is accelerated through a potential difference of 4000 volt, its de Broglie wavelength is λ . What will be the de Broglie wavelength of a deuteron when accelerated through a potential difference of 8000 volt?
The potential energy of a particle of mass m is given by U x = E o : 0 ≤ x ≤ 1 0 : x > 1 λ 1 and λ 2 are the de-Broglie wavelengths of the particle, when 0 ≤ x ≤ 1 and x > 1 respectively. If the total energy of particle is 2 E o , the ratio λ 1 λ 2 will be
In the following arrangement y = 1.0 mm, d = 0.24 mm and D = 1.2 m. The work function of the material of the emitter is 2.2 eV. The stopping potential V needed to stop the photo current will be
The eye can detect 5 x 10 4 photons per square metre per sec of green light λ = 5000 A o while the ear can detect 10 – 13 W / m 2 . The factor by which the eye is more sensitive as a power detector than the ear is close to
The curve between current (i) and potential difference (V) for a photo cell will be
The correct curve between the stopping potential (L) and, intensity of incident light (I)is
de Broglie wavelength of neutron having kinetic energy of 5 MeV is λ . Then what will be the de Broglie wavelength of α − particle having kinetic energy of 20 MeV?
The photoelectric threshold wavelength for potassium (work function being 2 eV) is
The correct graph between the maximum energy of a photoelectron and the inverse of wavelength of the incident radiation is given by the curve
The work function of a metal is 4.2 eV, its threshold wavelength will be
A photosensitive metallic surface has work function, hv o . If photons of energy 2 hv o fall on this surface, the electrons come out with a maximum velocity of 4 x 10 6 m./s. When the photon energy is increased to 5 hv o , then maximum velocity of photoelectrons will be
When photons of energy hv fall on an aluminium plate (of work function E o ), photoelectrons of maximum kinetic energy K are ejected. If the frequency of the radiation is doubled, the maximum kinetic energy of the ejected photoelectrons will be
The work functions for metals A, B and C are respectively 1.92 eV,2.0 eV and 5 eV. According to Einstein’s equation, the metals Which will emit photoelectrons for a radiation of wavelength 4100 A o are
Monochromatic light of frequency 6.0 x 10 14 Hz is produced by a laser. The power emitted is 2 x 10 – 3 W. The number of photons emitted. on the average, by the source per second is
A photocell employs photoelectric effect to convert
The momentum of a photon of energy 1 MeV in kg m/s will be
A 5 W source emits monochromatic light of wavelength 5000 A. When placed 0.5 m away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved to a distance of 1.0 m the number of photoelectrons liberated will be reduced by a factor of
The work function of a surface of a photosensitive material is 6.2 eV. The wavelength of the incident radiation forwhich the stopping potential is 5 eV lies in the
A particle of mass 1 mg has the same wavelength as an electron moving with a velocity of 3 x 10 6 ms -1. The velocity of the particle is
The number of photoelectrons emitted for light of a frequency v (higher than the threshold frequency ν o ) is proportional to
Monochromatic light of wavelength 667 nm is produced by a helium neon laser. The power emitted is 9 rnW. The number of photons arriving per second on the average at a target irradiated by this beam is
In photoelectric effect, the electrons are ejected from metals if the incident light has a certain minimum
The figure shows a plot of photo current versus anode potential i’or a photosensitive surface for three difrerent radiations. Which one of the following is a correct statement?
If alpha, beta and gamma rays carry same momentum, which has the longest wavelength?
If a photon has velocity c and energy E, then which of following represents its wavelength?
Sodium and copper have work functions 2.3 eV and 4.5 eV respectively. Then the ratio of their threshold wavelengths is nearest to
Two identical photo-cathodes receive light of frequencies f 1 and f 2 . If the velocities of the photo electrons (of mass m ) coming out are respectively v 1 and v 2 , then
The work function of a substance is 4.0 eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately
If the kinetic energy of a free electron doubles, its de-Broglie wavelength changes by the factor
In photoelectric effect, the K.E. of electrons emitted from the metal surface depends upon
The photoelectric effect can be understood on the basis of
If the threshold wavelength for sodium is 5420 A o , then the work function of sodium is
The light rays having photons of energy 1.8 eV are falling on a metal surface having a work function 1.2 eV. What is the stopping potential to be applied to stop the emitting electrons?
For photoelectric emission, tungsten requires light of 2300 A o . If light of 1800 A o wavelength is incident then emission
The magnitude of saturation photoelectric current depends upon
A photon of energy 8 eV is incident on metal surface of threshold frequency 1.6 x 10 15 Hz. The maximum kinetic energy of the photoelectrons emitted (in eV) (Take h = 6 x 10 – 34 Js).
The maximum velocity of an electron emitted by light of wavelength λ . incident on the surface of a metal of work function Φ, is
When green light is incident on the surface of metal, it emits photo-electrons but there is no such emission with yellow colour light. Which one of the colours can produce emission of photo-electrons?
An electron is moving through a field. It is moving (i) opposite an electric field (ii) perpendicular to a magnetic field as shown. For each situation the de Broglie wave length of electron
The maximum value of stopping potential in the following diagram is
The speed of an electron having wavelength of 10 – 10 m is
A photon of energy 4 eV is incident on a metal surface whose work function is 2 eV. The minimum reverse potential to be applied for stopping the emission of electrons is
Light of wavelength 4000 A o is incident on a metal plate whose work function is 2 eV. What is maximum kinetic energy of emitted photoelectron?
From the figure describing photoelectric effect we may infer correctly that
We wish to see inside an atom. Assuming the atom to have a diameter of 100 pm, this means that one must be able to resolve a width of say 10 pm. If an electron microscope is used, the minimum electron energy required is about
The figure shows different graphs between stopping potential ( V o ) and frequency (v) for photosensitive surface of cesium, potassium, sodium and lithium. The plots are parallel. Correct ranking of the targets according to their work function greatest first will be
The pressure exerted by an electromagnetic wave of intensity I(W m 2 ) on a non-reflecting surface is [c is the velocity of light]
In a photoelectric experiment work function of the metal surface is 3 eV and stopping potential is 2 volt then what percent of the energy of the photon of incident light appears as kinetic energy of fastest moving photo-electron?
The threshold wavelength of a metal surface is 500 nm. V is the maximum velocity of photo electrons when the wavelength of incident light is 400 nm. If the maximum velocity of photo electrons from the same metal surface is 2V, the wavelength of incident light is
de Broglie wavelength of a neutron particle having kinetic energy E is λ . What will be the de Broglie wavelength of a neutron particle having energy 9E?
When a 25 watt point source of power, emitting mono chromatic light of wavelength 4000 A o is kept at a distance of 50 cm from a photo sensitive surface of work function 2 eV. Then stopping potential needed to stop the most energetic emitted photo electrons is
The de-Broglie wavelength of the electron in the first excited state of hydrogen atom is
For the photo electric effect, the maximum kinetic energy E K of the emitted photo electrons is plotted against the frequency ν of the incident photons as shown in the figure. The slope of the graph gives
When photons of wavelength λ 1 are incident on an isolated sphere suspended by an insulated thread, the corresponding stopping potential is found to be Z. When photons of wave length λ 2 are used, the corresponding stopping potential was thrice the above value. If light of wavelength λ 3 is used, calculate the stopping potential for this case.
Photons of energy 2eV fall on a metal plate and release photo electrons with a maximum velocity v , by decreasing the wave length by 25% the maximum velocity of photo electrons is doubled. The work function of metal of the material of plate in eV is
Photoelectric emission is observed from a metallic surface for frequencies v 1 and v 2 of incident light v 1 > v 2 . If the maximum value of kinetic energies of photoelectrons emitted in these two cases are in ratio k 1 k 2 = 1 k , then find the threshold frequency of the metal surface
The electric field associated with a light wave is given by E = E 0 sin 1 . 57 × 10 7 m – 1 ( x – c t ) . Find the stopping potential (in eV) when this light is used in an experiment on photoelectric effect with a metal having work-function 1.9 eV.
Light of two different frequencies whose photons have energies 1 eV and 2.5 eV respectively, successively illuminates a metal of work function 0.5 eV. If the maximum kinetic energies of emitted electron is K 1 and K 2 respectively. The ratio K 2 K 1 is .
When a point source of monochromatic light is at a distance of 0.2 m from a photoelectric cell, the cut-off voltage and the saturation current are 0.6 volt and 18 mA respectively. If the same source is placed 0.6 m away from the photoelectric cell, then
Ultraviolet light of wavelength 300 nm and intensity 1.0 watt/m 2 falls on the surface of a photosensitive material. lf 1% of the incident photons produce photoelectrons, then the number of photoelectrons emitted from an area of 1.0 cm 2 of the surface is nearly
The ratio of de Broglie wavelength of a α -particle to that of a proton being subjected to the same magnetic field so that the radii of their paths are equal to each other assuming the field induction vector B is perpendicular to the velocity vectors of the α -particle and the proton is
In a photocell, bi-chromatic rays of light of wavelength 2475 Å and 6000 Å are incident on cathode whose work function is 4.8 eV. If a uniform magnetic field of 3 x 10 -5 tesla exists parallel to the plate, the radius of the path describe by the photoelectron will be (mass of electron =9 x 10 -31 kg)
The eye can detect 5 x 10 4 photons per square meter per sec of green light ( λ = 5000 Å ) while the ear can detect 10 -13 (W/m 2 ). The factor by which the eye is more sensitive as a power detector than the ear is close to
Two metallic plates A and B, each of area 5 x 10 -4 m 2 are placed parallel to each other at a separation of 1 cm. Plate B carries a positive charge of 33.7 pC. A monochromatic beam of light, with photons of energy 5 eV each, starts falling on plate A at t = 0, so that 10 16 photons fall on it per square meter per second. Assume that one photoelectron is emitted for every 10 6 incident photons. Also assume that all the emitted photoelectrons are collected by plate B and the work function of plate A remains constant at the value 2 eV. Electric field between the plates at the end of 10 seconds is
In the following diagram if V 2 > V 1 then
Out of a photon and an electron, the equation E = p c , is valid for
From the figure describing photoelectric effect, we may infer correctly that
The figure shows different graphs between stopping potential (V 0 ) and frequency (v) for photosensitive surface of cesium, potassium, sodium and lithium. The plots are parallel. Correct ranking of the targets according to their work function greatest first will be
How many photons are emitted per second by a 5 mW laser source operating at 632.8 nm?
If 5% of the energy supplied to a bulb is irradiated as visible light, how many quanta are emitted per second by a 100 W lamp? Assume wavelength of visible light as 5.6 x 10 -5 cm.
An electron of mass m e and a proton of mass m p are accelerated through the same potential difference. The ratio of the de Broglie wavelength associated with an electron to that associated with proton is
A modern 200 W sodium street lamp emits yellow light of wavelength 0.6 μ m. Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is
How many photons of a radiation of wavelength λ = 5 x 10 -7 m must fall per second on a blackened plate in order to produce a force of 6.62 x 10 -5 N?
Find the ratio of de Broglie wavelength of a proton and an alpha-particle which have been accelerated through same potential difference.
Two electrons are moving with same speed v. One electron enters a region of uniform electric field while the other enters a region of uniform magnetic field, then after some time de Broglie wavelengths of two are λ 1 and λ 2 respectively. Now,
An electron is moving through a field. It is moving (i) opposite an electric field (ii) perpendicular to a magnetic field as shown. For each situation the de-Broglie wave length of electron
Which of the following is not a possible de-Broglie’s wavelength of a particle, which moves inside a cubical box of side length L, without losing any energy (elastically colliding with walls of cube)?
If the momentum of an electron is changed by ∆ p , then the de-Broglie wavelength associated with it changes by 0.50%. The initial momentum of the electron will be
There are n 1 photons of frequency γ 1 in a beam of light. In an equally energetic beam, there are n 2 photons of frequency γ 2 .Then the correct relation is
Electrons are accelerated in television tubes through potential differences of about 10 kV. The highest frequency of the electromagnetic waves emitted when these electrons strike the screen of the tube is
With respect to electromagnetic theory of light, the photoelectric effect is best explained by statement
In a photoelectric effect, electrons are emitted
If the intensity of radiation incident on a photocell be increased four times, then the number of photoelectrons and the energy of photoelectrons emitted respectively become
The work function of a metal is W and λ is the wavelength of the incident radiation. There is no emission of photoelectrons when
If a surface has work function of 3.00 eV, the longest wavelength of light which will cause the emission of electrons is
The work function for sodium surface is 2.0 eV and that for aluminum surface is 4.2 eV. The two metals are illuminated with appropriate radiations so as to cause photoemission. Then
A metal surface is illuminated by a light of given intensity and frequency to cause photoemission. If the intensity of illumination is reduced to one-fourth of its original value, then the maximum KE of emitted photoelectrons will become
Lights of two different frequencies whose photons have energies 1.0 eV and 2.5 eV, respectively, successively illuminate a metal whose work function is 0.5 eV. The ratio of the maximum speeds of the emitted electrons will be
Given that a photon of light of wavelength 10,000 Å has an energy equal to 1.23 eV. When light of wavelength 5000 Å and intensity I o falls on a photoelectric cell, the saturation current is 0.40 x 10 -6 A and the stopping potential is 1.36 V; if the intensity of light is made 4I 0 , then the stopping potential will become
Given that a photon of light of wavelength 10,000 Å has an energy equal to 1.23 eV. When light of wavelength 5000 Å and intensity I o falls on a photoelectric cell, the saturation current is 0.40 x 10 -6 A and the stopping potential is 1.36 V; if the intensity of light is made 4I 0 , then the stopping potential will become
Given that a photon of light of wavelength 10,000 Å has an energy equal to 1.23 eV. When light of wavelength 5000 Å and intensity I o falls on a photoelectric cell, the saturation current is 0.40 x 10 -6 A and the stopping potential is 1.36 V; if the intensity of light is made 4I 0 , then the saturation current will become
Given that a photon of light of wavelength 10,000 Å has an energy equal to 1.23 eV. When light of wavelength 5000 Å and intensity I o falls on a photoelectric cell, the saturation current is 0.40 x 10 -6 A and the stopping potential is 1.36 V; if the wavelength is changed to 4000 Å , then stopping potential will become
Given that a photon of light of wavelength 10,000 Å has an energy equal to 1.23 eV. When light of wavelength 5000 Å and intensity I o falls on a photoelectric cell, the saturation current is 0.40 x 10 -6 A and the stopping potential is 1.36 V; then work function is
When a centimeter thick surface is illuminated with light of wavelength λ , the stopping potential is V. When the same surface is illuminated by light of wavelength 2 λ ,the stopping potential is V/3. Threshold wavelength for the metallic surface is
The work function of a metallic surface is 5.01 eV. The photoelectrons are emitted when light of wavelength 2000 Å falls on it. The potential difference applied to stop the fastest photoelectrons is h = 4.14 × 10 − 15 eVs
Light of wavelength λ strikes a photoelectric surface and electrons are ejected with kinetic energy K. If K is to be increased to exactly twice its original value, the wavelength must be changed to λ ‘ such that
The KE of the photoelectrons is E when the incident wavelength is λ /2. The KE becomes 2E when the incident wavelength is λ /3. The work function of the metal is
Light from a hydrogen discharge tube is incident on the cathode of a photoelectric cell. The work function of the cathode surface is 4.2 eV. In order to reduce the photocurrent to zero the voltage of the anode relative to the cathode must be made
If λ 0 stands for mid-wavelength in the visible region, the de Broglie wavelength for 100 V electrons is nearest to
A photon of wavelength 4400 Å is passing through vacuum. The effective mass and momentum of the photon are respectively
A proton when accelerated through a potential difference of V volt has a wavelength λ associated with it. An α -particle in order to have the same λ must be accelerated through a potential difference of
The threshold frequency for certain metal is v 0 . When light of frequency 2v 0 is incident on it, the maximum velocity of photoelectrons is 4 x 10 6 ms -1 . If the frequency of incident radiation is increased to 5v 0 , then the maximum velocity of photoelectrons will be
In Davison Germer experiment, the sudden peak in intensity of the Intensity vs potential difference curve ( θ = 50 0 , V = 54 v o l t ) arises because of
The correct statements among the following A) Davisson and Germer experiment proves wave nature of electron. B) Photoelectric effect proves particle nature of light C) Production of X-ray is reverse of photoelectric effect. D) Wavelength of characteristic X-ray decreases with increase in accelerating potential.
The work function of a metal is 4ev. For emitting photo electron of zero velocity from the surface of this metal, The wave length of incident light required must be
A bomb projected from ground at an angle θ θ ≠ 90 ° with horizontal explodes into two fragments of equal mass at top most point of its trajectory. If one of the fragment returns to point of projection then ratio of de-Broglie wavelength of second fragment just after explosion to bomb just before explosion is :
Photons with energy 5eV are incident on a cathode C, on a photoelectric cell. The maximum energy of the emitted photoelectrons is 2eV. When photons of energy 6eV are incident on C, no photoelectrons will reach the anode A if the potential of A relative to C is
What is the de Broglie wavelength of an electron with a velocity of 10 7 m/s
Work function of nickel is 5.01 eV. When ultraviolet radiation of wavelength 200 A o is incident on it, electrons are emitted. What will be the maximum velocity of emitted electrons?
Figure shows the plot of the stopping potential versus the frequency of the light used in an experiment on photoelectric effect. The ratio h/e is
The kinetic energy of most energetic electrons emitted from a metallic surface is doubled when the wavelength , λ of the incident radiation is changed from 400 nm to 310 nm. The work function of the metal is
The maximum velocity of electrons emitted from a metal surface is v. What would be the maximum velocity if the frequency of incident light is increased by a factor of 4?
When a certain metallic surface is illuminated with monochromatic light of wavelength λ the stopping potential for photoelectric current is 3V 0 and when the same surface is illuminated with light of wavelength 2 λ , the stopping potential is V 0 .The threshold wavelength of this surface for photoelectric effect is
Threshold frequency for a certain metal is v 0 . When light of frequency 2v 0 is incident on it, the maximum velocity of photoelectrons is 4 x 10 8 cm s -1 . If frequency of incident radiation is increased to 5v 0 , then the maximum velocity of photoelectrons, in cm s -1 , will be
Monochromatic light incident on a metal surface emits electrons with kinetic energies from zero to 2.6 eV. What is the least energy of the incident photon if the tightly bound electron needs 4.2 eV to remove?
Light of wavelength 0.6 pm from a sodium lamp falls on a photocell and causes the emission of photoelectrons for which the stopping potential is 0.5 V. With light of wavelength 0.4 μ m from a mercury vapor lamp, the stopping potential is 1.5 V. Then, the work function [in electron volts] of the photocell surface is
Ultraviolet light of wavelength 300 nm and intensity 1.0 W m -2 falls on the surface of a photosensitive material. If one per cent of the incident photons produce photoelectrons, then the number of photoelectrons emitted per second from an area of 1.0 cm 2 of the surface is nearly
An image of the sun is formed by a lens, of the focal length of 30 cm, on the metal surface of a photoelectric cell and a photoelectric current I is produced. The lens forming the image is then replaced by another of the same diameter but of focal length 15 cm. The photoelectric current in this case is
A homogeneous ball (mass=m) of ideal black material at rest is illuminated with a radiation having a set of photons (wavelength – λ ),each with the same momentum and the same energy. The rate at which photons fall on the ball is n. The linear acceleration of the ball is
A cesium photocell, with a steady potential difference of 60 V across it, is illuminated by a small bright light placed 1 m away. When the same light is placed 2m away, the electrons crossing the photocell
The eye can detect 5 x 10 4 photons (m 2 s) -1 of green light ( λ =5000 A o ), while ear can detect 10 -13 W m -2 . As a power detector, which is more sensitive and by what factor?
A photon of wavelength 0.1 A o is emitted by a helium atom as a consequence of the emission of photon. The KE gained by helium atom is
A monochromatic source of light is placed at a large distanced from a metal surface. Photoelectrons are ejected at rate n, the kinetic energy being E. If the source is brought nearer to distance d/2,the rate and kinetic energy per photoelectron become nearly
An α -particle and a proton are fired through the same magnetic field which is perpendicular to their velocity vectors. The α -particle and the proton move such that radius of curvature of their paths is same. Find the ratio of their de Broglie wavelengths.
If the short wavelength limit of the continuous spectrum coming out of a Coolidge tube is 10 A o , then the de Broglie wavelength of the electrons reaching the target metal in the Coolidge tube is approximately
All electrons ejected from a surface by incident light of wavelength 200 nm can be stopped before traveling 1 m in the direction of a uniform electric field of 4NC -1 . The work function of the surface is
A sodium metal piece is illuminated with light of wavelength 0.3 μ m . The work function of sodium is 2.46 eV. For this sifuation, mark out the correct statement(s).
The kinetic energy of a particle is equal to the energy of a photon. The particle moves at 5% of the speed of light. The ratio of the photon wavelength to the de Broglie wavelength of the particle is [No need to use relativistic formula for the particle.]
The potential energy of a particle of mass m is given by U ( x ) = E 0 ; 0 ≤ x ≤ 1 0 ; x > 1 λ 1 and λ 2 are the de-Broglie wavelengths of the particle, when 0 ≤ x ≤ 1 and x > 1 respectively. If the total energy of particle is 2E 0 , the ratio λ 1 λ 2 will be
Let a light beam of total intensity 1 μ W cm − 2 falls on a clean iron sample piece with J work function 4.5 eV and of 1.0 cm 2 area. Assume that iron sample reflects 96% of light and that only 3% ofthe absorbed energy lies in the violet region which can cause photoemission (of wavelength 250 nm). Number of electrons emitted will be
As energy associated with changes with its wavelength, often the reciprocal of the wavelength 1 / λ . is used to describe energy associated with that wavelength. Then, mark the correct equivalence.
In the figure shown electromagnetic radiations of wavelength 200 nm are incident on the metallic plate A. The photo electrons are accelerated by a potential difference 10 V. These electrons strike another metal plate B from which electromagnetic radiations are emitted. The minimum wavelength of the emitted photons is 100 nm. If the work function of the metal ‘A’ is found to be 1.9 N eV. The value of N is Use h v = 12400 eV Å, use R ch − 13.6 eV .
When light of wavelength 300 nm (nanometer) falls on a photoelectric emitter, photoelectrons are liberated. For another emitter, however light of 600 nm wavelength is sufficient for creating photoemission. What is the ratio of the work functions of the two emitters?
Threshold wavelength for photoelectric effect on sodium is 5000 A o . The work function (in x 10 -19 J) is .
Light of two different frequencies whose photons have energies 1 eV and 2.5 eV respectively, successively illuminates a metal of work function 0.5 eV. If the maximum kinetic energies of emitted electron is K 1 and K 2 respectively. The ratio K 2 K 1 is
An α -particle and a proton are fired through the same magnetic fields which is perpendicular to their velocity vectors. The α -particle and the proton move such that radius of curvature of their path is same. The ratio of their de-Broglie wavelengths is
Light of wavelength 400 nm is incident continuously on a Cesium ball (work function 1.9 eV). Find the maximum potential (in V) to which the ball will be charged.
In the photoelectric experiment, if we use a monochromatic light, the I-V curve is as shown. If work function of the metal is 2 eV, estimate the power of light used (in W). (Assume efficiency of photoemission = 10 -3 % i.e. number of photoelectrons emitted are 10 -3 % of number of photons incident on metal.)
A small potassium foil is placed (perpendicular to the direction of incidence of light) a distance r (= 0.5 m) from a point light source whose output power P 0 is 1.0 W. Assuming wave nature of light how long (in s) would it take for the foil to soak up enough energy (= 1.8 eV) from the beam to eject an electron? Assume that the ejected photoelectron collected its energy from a circular area of the foil whose radius equals the radius of a potassium atom (1.3 x 10 -10 m).
A photo cell is illuminated by a small bright source placed at 1m away. When the same source of light is placed 2m away, which of the following is true about the electrons emitted by the photo cathode?
Photoelectric experiment is conducted separately in the same experimental set up using light of same intensity but of different frequencies f 1 and f 2 f 1 > f 2 . If i be the photo current and V be the applied potential, then which of the following graphs correctly shows the variation of i with V?
If de Broglie wavelength of an electron and a position are same, then which quantity / quantities will be the same for both?
An electron and a positron are released from rest at same separation from each other. Due to mutual electro static force of attraction they start moving towards each other. Just before collision
Variation of maximum kinetic energy of photoelectron with wavelength of incident radiation is correctly shown
What should be the velocity of an electron so that its momentum becomes equal to that of a photon of wavelength 5200 A 0 ?
Which among the following shows the particle nature of light?
Which crystal is used in the Davisson – Germer experiment?
For a photosensitive material when it is exposed to an electromagnetic radiation of frequency more than its threshold value then the wrong statement is
The energy of a photon of light of wavelength 450 nm is:
The number of photoelectrons emitted by metallic surface when photons of frequency v is incident on it (higher than the threshold frequency v 0 ) is proportional to
The stopping potential for photoelectrons emitted from a surface illuminated by light wavelength of 5893 Å is 0.36 V. Calculate the maximum kinetic energy of photoelectrons.
In photo-emissive cell, with exciting wavelength λ, the fastest electron has speed v. If the exciting wavelength is changed to 3 λ /4, the speed of the fastest emitted electron will be:
In a photoelectric experiment, electrons are ejected from metal X and Y by light of intensity I and frequency f The potential difference V required to stop the electrons is measured for various frequencies. If Y has a greater work function than which one of the following graphs best illustrates the expected results?
The de Broglie wavelength of an electron and the wavelength of a photon are the same. The ratio between the energy of that photon and the momentum of that electron is (c is velocity of light, h is Planck’s constant)
For intensity I of a light of wavelength 5000 A 0 the photoelectron saturation current is 0.40 μA and stopping potential is 1.36 V, the work function of the metal is:
The kinetic energy of electron and proton is 10 − 32 J . Then the relation between their de-Broglie wavelength is :
A radiation of energy E falls normally on a perfectly reflecting surface. The momentum transfer to the surface is
If the kinetic energy of a free electron doubles, its de-Broglie wavelength changes by a factor
If the kinetic energy of the moving particle is E, then the de-Broglie wavelength is
An electron of mass m, when accelerated through a potential V has de-Broglie wavelength λ the de-Broglie wavelength associated through the same potential difference will be
What will be the ratio of the de-Broglie wavelength of proton and o particle of same energy
Two identical photo cathodes receive light of frequencies f 1 and f 2 If the velocities of the photo electrons (of mass m) coming out are respectively v 1 and v 2 ,then
Ultraviolet radiation of 6.2 eV falls on an aluminum surface (work function 4.2 eV). The kinetic energy in joule of the fastest electron emitted is approximately
The threshold frequency for potassium (in joule) is 3 ⋅ 0 × 10 14 per sec. The work function of potassium is
If the energy of a photon corresponding to a wavelength of 6000 Å is 3.32 x10 -19 joule, the photon energy (in joule) for a wavelength of 4000 Å will be
When a point light source, of power E emitting monochromatic light of wavelength λ is kept at a distance r from a photosensitive surface of work -function ϕ and area s, then number of photons striking the surface per unit time is
The minimum light intensity that can be perceived by the eye is about 10 -10 W /m 2 .The number of photons of wavelength 5.6 x10 -7 m that must enter the pupil of are 10 -6 m 2 per sec for vision is approximately (use h =6.6×10 -34 Joule -sec)
10 20 photons of wavelength 660 nm are emitted per second from a lamp. What is the wattage of the lamp ? Planck’s constant = 6.6 x10 -34 J-s
The threshold wavelength for a metal of work -function W 0 is λ 0 The threshold wavelength for a metal having work-function 3 Wo will be
When a centimeter thick surface is illuminated with light of wavelength λ , stopping potential is V, when the same surface is illuminated by light of wavelength 2 λ , stopping potential is V /3. Threshold the same surface is illuminated by light of is
Energy required to remove an electron from an aluminum surface is 4.2 eV, lf light of wavelength 2000 A falls on the surface, the velocity of fastest electron erected from the surface is
The maximum velocity of an electron emitted by light of wavelength λ incident on the surface of a metal of work function W 0 is
The energy of a photon is equal to the kinetic energy of a proton. The energy of the photon is E. Let λ 1 , be the de-Broglie wavelength of the proton and λ 2 , be the wavelength of the photon. The ratio λ 1 / λ 2 is proportional to
The figure (1) shows the variation of photo current with anode potential for a photo-sensitive surface for three different radiations. Let I a , I b and I c be the intensities and f a , f b and f c be the frequencies for the curves a.b and c respectively
Photon of frequency v has a momentum associated with it. If c is the velocity of light, the momentum is
In photoelectric effect, the photo-current
A photosensitive metal is not emitting photo-electrons when irradiated. It will do so when threshold is crossed. To cross threshold we need to 6. increase
In photoelectric effect the number of photo-electrons emitted is proportional to
The frequency and the intensity of a beam of light falling on the surface of photo-electric material are 7, increased by a factor of two. This will
The frequency of incident light falling on a photosensitive metal plate is doubled, the kinetic energy of the emitted photo-electron is
A photo-electric cell converts
When yellow light is incident on a surface no electrons are emitted while green light can emit. ff red light is incident on the surface then
The photoelectdc threshold of a certain metal is 3000 Å . If the radiation of 2000 Å is incident on the metal
When a monochromatic point-source of light is at a distance of 0.2 m from a photo-electric cell, the cut-off voltage and the saturation current are respectively 0.6 V and 18’0 mA. If the same source is placed 0.6 m away from the photoelectric cell, then
When light of wavelength 300 nm (manometer) falls on a photo electric emitter, photo electrons are liberated. For another emitter, however, light of 600 nm wavelength is sufficient for creating photo-emission. What is the ratio of the work-functions of the two emitter ?
Radiation of two photon energies twice and five times the work-function of metal are incident successively on the metal surface. The ratio of the maximum velocity of photo electrons emitted in the two cases will be
Light of wavelength 0.6pm from a sodium lamp falls on a photo cell and causes the emission o{ photo-electrons for which the stopping potential is 0.5 V With light of wavelength 0.40 pm from a mercu4r vapour lamp the stopping potential is 1’5 V then work-function in electron volt of the photo cell surface is
A surface irradiated with light of wavelength 480 nm gives out electrons with maximum velocity 2 v m/s, the cut off wavelength being 600 nm. The same surface would release electrons with maximum velocity 2 v m/s, if it is irradiated by light of wavelength
The threshold frequency for a certain metal is v 0 When light of frequency v = 2 v 0 is incident on it, the maximum velocity of photo electrons is 4 x 10 6 m/s’ If the frequency of incident radiation is increased to 5 v 0 , then the maximum velocity of photo electrons in m/s will be
The maximum kinetic energy of photo electrons emitted from a surface when photons of energy 6 eV fall on it is 4 eV, The stopping potential in volt is
A particle of mass M at rest decays into two particles of masses r?11 and m 2 having non-zero velocities. The ratio of the de Broglie wavelengths of the particles, λ 1 , λ 2 is
The maximum kinetic energy K max of photo-electrons emitted in a photoelectric cell is measured using lights of various frequencies v,. The slope of the graph is equal to
In photo-electric effect, the slope of straight line graph between stopping potential (V 0 ) and frequency of incident light (v) gives
The stopping potential as a function of frequency of incident radiation is plotted for two different photoelectric surfaces A and B. The graph shows that the work function of A is
The kinetic energy), (E K ) of a photo-electron varies with the frequency v of the incident radiation ac which of the following graphs ?
The work-functions for three different metals A, B, and C are W A , W B and W C respectively with W A > W B > W C The gaph between stopping potential V 0 and frequency v of incident radiation for them would look like
In a photo-missive cell, with exciting wavelength λ the fastest electron has speed v. If the exciting wavelength is changed to 3 λ / 4 the speed of the fastest emitted electron will be
The electric field associated with a light wave is E = E 0 sin 1 ⋅ 57 × 10 7 ( x − c t ) where x is in metre and t is in second. If this light is used to produce photo-electric emission from the surface of a metal of work-function 1’9 eV, then the stopping potential will be
A small metal plate (work-function Ws) is kept at a distance d from a singly ionised fixed ion. A monochromatic light beam is incident on the metal plate and photoelectric are emitted. The maximum wavelength of light so that the photo-electrons may go round the ions along a circle is
when a point light source, of power P emitting monochromatic light of wavelength λ is kept at a distance α from a photo-sensitive surface of work-function W 0 and area A which of the expressions is wrong
A surface is irradiated with ultra violet radiation of wavelength 0.2 μ m. if the maximum velocity of electron liberated from the surface is 8.8 x 10 5 m/s then the work function of the surface is
When a surface 1 cm thick is illuminated with light of wavelength λ the stopping potential is V 0 but when the same surface is illuminated by light of wavelength 3 λ the stopping potential is V 0 /6. the threshold wavelength for metallic surface is
The kinetic energy of electrons is 10 -20 J and the photons also have the same energy. The wavelengths associated with these particles are λ e and λ ph respectively. These wavelengths are related in the following way
Find the ratio of de-Broglie wavelength of molecules of hydrogen and helium which are at temperature 27 ∘ C and 127 ∘ C respectively
An electron and a photon have the same de Broglie wavelength. Then the kinetic energy of the electron is
Which of the following graphs represents the variation of particle momentum and associated de-Broglie wavelength.
What is the de Broglie wavelength of an electron of energy 180 eV? Mass of electron = 9 × 10 − 31 kg and Planck’s constant = 6.6 × 10 − 34 Js.
At an incident radiation frequency of v 1 , which is greater than the threshold frequency, the stopping potential for a certain metal is V 1 . At frequency 2v 1 , the stopping potential is 3V 1 . If the stopping potential at frequency 4v 1 is n V 1 , then n is ………
1.5 mW of 400 nm light is directed at a photoelectric cell. If 0.1 % of the incident photons produce photoelectrons, find the current (in μ A) in the cell.
An electron in hydrogen-like atom makes a transition from nth orbit and emits radiation corresponding to Lyman series. If de-Broglie wavelength of electron in nth orbit is equal to the wavelength of radiation emitted, find the value of n. The atomic number of atom is 11.
