In Bohr’s model of hydrogen atom, let PE represent potential energy and TE the total energy. In going to a higher orbit,
In Hydrogen spectrum the shortest wavelength in Balmer series is λ . The shortest wavelength in the Brackett series will be
Electrons from n=2 to n=1 in Hydrogen atom is made to fall on a metal surface with work function 1.2ev. The maximum velocity of photo electrons emitted is nearly equal to
The speed of the electron in a hydrogen atom in the n = 3 level is
Consider 3rd orbit of He + (Helium), using non-relativistic approach, the speed of electron in this orbit will be [ given K = 9 x 10 9 constant, Z = 2 and h (Planck’s Constant) = 6 . 6 × 10 – 34 J s
Angular momentum of an electron in a hydrogen atom is proportional to
When an electron jumps from a level n = 4 to n = 1, the momentum of the recoiled hydrogen atom will be
The magnetic moment ( μ ) of a revolving electron around the nucleus varies with principal quantum number n as
According to Bohr’s theory of hydrogen atom, the angular momentum of an electron in any orbit of hydrogen atom is
The ratio of the areas of the circular orbits of an electron for the first excited state in a hydrogen atom to that for the ground state is
An electron revolve round the nucleus of charge Ze. In order to excite the electron from state n=2 to n=3 the energy required is 47.2 eV. What is the value of Z ?
Hydrogen atom in ground state is excited by a monochromatic radiation of λ = 975 A ο . Number of spectral lines in the resulting spectrum emitted will be
The largest distance between the interatomic planes of a crystal is 2 x 10 – 7 cm. The upper limit for the wavelength of X-rays which can be usefully studied with this crystal is
The total energy of an electron in an atom in an orbit is -3.4 eV . Its kinetic and potential energies are, respectively
The radius of the first permitted Bohr orbit, for the electron, in a hydrogen atom equals 0.51 Å and its ground state energy equals –13.6 eV. If the electron in the hydrogen atom is replaced by muon ( μ –) [charge same as electron and mass 207 m e ], the first Bohr radius and ground state energy will be,
Let the potential energy of Hydrogen atom in the ground state be zero. Then its orbital energy in the first excited state will be
The radius of the Bohr orbit in the ground state of hydrogen atom is 0 .5 A 0 . Then the radius of the orbit of the electron in the third excited state of He + ion is
In a stationary hydrogen atom, an electron jumps from n=2 to n=1, then linear momentum of the atom is
If a hydrogen atom emits a photon of energy 12.75 eV and returns to its ground state, change in its orbital angular momentum is
The difference between excitation energy and binding energy of electron in a He + ion is 42.31 eV. The energy quantum number of the excited state is
The figure indicates the energy levels of a certain atom. When the system moves from 2E level to E, a photon of wavelength λ is emitted. The wavelength of a photon produced in transition from level 4 E 3 to level E is
Electric conduction in a semiconductor takes place due to
Bohr magneton is
Moseley's law for characteristic X-rays is = a (Z – b). In this
when filament current is increased
The x-ray beam coming from an x-ray tube will be
If the current in the circuit for heating the filament is increased, the cut off wavelength
According to Moseley’s law the frequencies of spectral lines of x-rays depends upon the following characteristics of the target element its
Which of the following statement is correct
Molybdenum is used as a target for production of x-rays, because it is
If the potential difference applied to the tube is doubled and the separation between the filament and the target is also doubled, the cut off wavelength will
Intensity of X – rays depends on a) nature of the target b) filament current
The graph between frequency frequency of x-rays and the atomic number z is
The energy of continuous x-ray photon comes from
Hydrogen atom does not exhibit x-ray because
According to moselay’s law, the frequency ( ν ) of the K α line and the atomic number (z) of the element have the relation (C is a constant)
According to Moseley’s law, the frequency ( ν ) of the K α line and the atomic number (z) of the element have the relation (A and B) are constants
If a voltage applied to an X-ray tube is increased to 1.5 times the minimum wavelength ( λ min ) of at X-ray continuous spectrum shifts by Δλ = 26 pm. The initial voltage applied to the tube is
Energy required to completely separate the electron and proton in a hydrogen atom is ground state in Joule is
Angular momentum of the electron in a hydrogen atom is 3 h 2 π . Then energy of the electron is
Transitions between three energy levels in a particular atom give rise to three spectral lines of wavelengths, in increasing magnitudes, λ 1 , λ 2 and λ 3 . Which one of the following equations correctly relates λ 1 , λ 2 and λ 3 ?
If λ 1 and λ 2 are the wavelengths of the first members of the Lyman and Paschen series, respectively, then λ 1 : λ 2 is
If one were to apply Bohr model to a particle of mass ‘m’ and charge ‘q’ moving in a plane under the influence of a magnetic field ‘B’, the energy of the charged particle in the nth level will be :
Out of the following which one is not a possible energy for a-photon to be emitted by hydrogen atom according to Bohr’s atomic model?
If the wavelength of first member of Balmer series of hydrogen spectrum is 6564 A o , the wavelength of second member of Balmer series will be :
Hydrogen atom in ground state is excited by a monochromatic radiation of λ = 975 A o . Number of spectral lines in the resulting spectrum emitted will be
Frequency of the series limit of Balmer series of hydrogen atom interms of Rydlberg constant R and velocity of light c is
The ionization potential of H atoms is 13.6 V. The energy difference between n = 2 and n = 3 levels is nearest to
An electron in a hydrogen atom makes a transition n 1 n 2 , where n 1 and n 2 are principal quantum numbers of the states. Assume the Bohr’s model to be valid. The time period of the electron in the initial states is eight times to that of final state. What is ratio of n 1 /n 2
The wave number of energy emitted when electron jumps from fourth orbit to second orbit in hydrogen in 20,497 cm -1 . The wave number of energy for the same transition in He + is
In an excited hydrogen atom, when the electron jumps from nth energy level to (n-1)th energy level, wavelength of emitted radiation is λ , when the electron jumps from (n-1)th energy level to (n-2)th energy level, wavelength of emitted radiation is K λ . Then what will be the wavelength of emitted radiation when the electron jumps from nth energy level to (n-2)th energy level?
For an atom of ion having single electron, the following wavelengths are observed. What is the value of missing wavelength x ?
The radius of first Bohr orbit in hydrogen atom is 0.5 Å and the speed of electron in this orbit is 2 × 10 6 m /s then the value of equivalent electric current will be
An excited hydrogen atom returns to ground state. The wavelength of emitted photon is λ The principal quantum number of the excited state will be
In Bohr model of hydrogen atom
E n and J n denote the total energy magnitude and the angular momentum of an electron in the n th allowed orbit of a Bohr atom, Then
In X-ray spectrum, transition of an electron from an outer shell to an inner shell gives a characteristics X-ray spectral line. If we consider the spectral lines K β , L β and M α , then
An electron revolve round the nucleus of a hydrogen like atom of atomic no 4. In order to excite the electron from state n=2 to n=3 the energy required is
The ratio of kinetic energy to the total energy of an electron in a Bohr orbit of the hydrogen atom, is
Given the value of Rydberg constant is 10 7 m – 1 , the wave number of the last line of the Balmer series in hydrogen spectrum will be
When the electron jumps from a level n = 4 to n = 1 the momentum of recoiled hydrogen atom will be
When an α -particle of mass m moving with velocity v bombards on a heavy nucleus of charge Z e , its distance of closest approach from the nucleus depends on m as
An α -particle of 7 MeV energy strikes with a nucleus of uranium at stationary at an scattering angle of 180 o . The nearest distance upto which α -particle reaches the nucleus will be of the order of
Ratio of longest wave lengths corresponding to Lyman and Balmer series in hydrogen spectrum is
In the spectrum of hydrogen, the ratio of the longest wavelength in the Lyman series to the longest wavelength in the Balmer series is
Electrons of mass m with de-Broglie wavelength λ fall on the target in an X -ray tube. The cutoff wavelength λ 0 of the emitted X -ray is
If an electron in a hydrogen atom jumps from the 3 r d orbit to the 2 r d orbit, it emits a photon of wavelength λ . When it jumps from the 4 r d orbit to the 3 r d orbit, the corresponding wavelength of the photon will be
An electron in hydrogen atom makes a transition n 1 n 2 where n 1 a n d n 2 are principal quantum numbers of the two states. Assuming Bohr’s model to be valid, the time period of the electron in the initial state is eight times that in the final state. The possible values of n 1 a n d n 2 are
A neutron have speed u makes head on collision with a hydrogen atom in ground state at rest. Find minimum K.E. of neutron for which no elastic collision is possible
The ratio of wavelengths of the last line of Balmer series and the last line of Lyman series is
For which one of the following, Bohr model is not valid?
The total energy of an electron in the n t h stationary orbit of the hydrogen atom can be obtained by
An orbital electron in the ground state of hydrogen has an angular momentum L 1 , and an orbital electron in the first excited state in doubly ionized Lithium has an angular momentum L 2 . Then
Moseley’s law for characteristic X-rays is v = a ( Z − b ) . In this,
The voltage applied to an X-ray tube is 18KV. The maximum mass of photon emitted by the X-ray tube will be:
If the longest wavelength in the ultraviolet region of hydrogen spectrum is λ 0 then the shortest wavelength in its infrared region is :
A photon of energy 10.2 eV corresponds to light of wavelength λ 0 . Due to an electron transition from n = 2 to n = 1 in a Hydrogen atom, light of wavelength λ is emitted. If we take into account the recoil of the atom when the photon is emitted, then
A hydrogen atom in an excited state emits a photon which has the longest wavelength of the Paschen series. Further emissions from the atom cannot include the
A hydrogen – like ion having wavelength difference between first line of Balmer and Lymann series is 593 A o . Then atomic number of the ion is
The transition from the state n = 4 to n = 3 in a hydrogen like atom results in ultraviolet radiation. Infra red radiation will be obtained in the transition
Balmer gives an equation for wavelength of visible radiation of H-spectrum as λ = kn 2 n 2 − 4 . The value of k in terms of Rydberg’s constant R is
A photon of energy 15 eV collides with a stationary H-atom. Due to this collision, H-atom gets ionized. The maximum kinetic energy of emitted electron is
The acceleration of electron in the first orbit of hydrogen atom is
Speed of electron in the ground state of hydrogen atom is V 0 . Then speed of electron in the third excited state of hydrogen atom is —
Stopping potential for the most energetic electron at a distance of 0.5 m for the target metal in an experiment of photoelectricity is V 0 .Then in the same experimental set-up stopping potential at a distance of 1 m from the target metal will be —-
The ratio of ionization energy of hydrogen atom to that of hydrogen like lithium ion is, according to Bohr’s theory
How many times larger is the spacing between the energy levels with n = 3 and n = 4, than the spacing between the energy levels with n = 8 and n = 9 for a hydrogen like atom or ion?
An alpha-particle is projected towards a stationary Cu nucleus, an Au nucleus and an Ag nucleus with same speed from a large distance. The distances of closest approaches were found to be d 1 , d 2 and d 3 respectively. Which of the following is correct?
The first Bohr radius of Hydrogen atom is R . The second Bohr radius of H e + will be
X – ray are not used for radar purposes , because they are not :
If doubly ionized lithium atom is hydrogen like with atomic number 3, the wavelength of radiation required to excite the electron in L i + + from the first to the third Bohr orbit and the number of different spectral lines observed in the emission spectrum of the above excited system are
The characteristic X-ray radiation is emitted when
The energy of the highest energy photon of Balmer series of Hydrogen spectrum is close to
The energy diagram for a Hydrogen like atom is shown in the figure. The radius of its first Bohr orbit is?
Angular momentum of an electron in a hydrogen atom is proportional to
In hydrogen atom, if the difference in the energy of the electron in n = 2 and n = 3 orbits is E, the ionization energy of hydrogen atom is :
If ω be be the angular speed of the electron in the nth orbit of the hydrogen atom, then
Energy of singly ionized helium atom in an excited state is equal to the energy of a hydrogen atom in first excited state. Then angular momentum of the electron of the helium ion is
If L be the orbital angular momentum of an hydrogen atom and r be radius of the atom then
The spectrum of a hydrogen – like ion in the Third Balmer line has a wavelength of 108.5 nm. Then number of protons in the nucleus of the ion is
The ratio of radius of α − particle to that of sulphur nucleus is
A doubly ionized Li 2 + ion in the ground state absorbs 108.8 eV of energy. Find the increase in angular momentum of electron. take h = 6 .63 × 10 − 34 J − s
A hydrogen like atom of atomic number Z is in excited state of quantum number 3n. The maximum energy which can be emitted by atom is 404 eV. If it makes the transition to quantum state n, a photon energy 40.4 eV is emitted. The value of n will be
Consider a photon of continuous X-ray and a photon of characteristic X-ray of the same wave-length. Which of the following is different for the two photons
The wave length λ of the K α line of characteristic x-ray spectra varies with atomic number approximately
Which of the following statements about X-rays is wrong ?
The target in an X-ray tube should be of a material which has
The characteristic x-rays are produced when
X-rays can be used
The energy of a photon of characteristic x-ray from a Coolidge tube comes from
According to Moseley's law, the frequency of a spectral line in X–ray spectrum varies as
The potential difference applied to an x-ray tube is increased. As a result for the emitted radiation a) the intensity increases b) the minimum wavelength increases c) intensity remains unchanged d) the minimum wavelength decreases
X-rays and γ -rays of the same energies may be distinguished by
The continuous X-rays spectrum produced by an X-ray machine at constant voltage has
Molybdenum is used as a target element for production of X-rays because it is
Which of the following is accompanied by the characteristic X-ray emission?
In an X-rays tube, the intensity of the emitted X-rays beam is increased by
The energy of a photon of characteristic X-rays from a Coolidge tube comes from
What determines the hardness of the X-rays obtained from the Coolidge tube?
Penetrating power of X-rays can be increased by
Penetrating power of X-rays does not depend on
The wavelength of X-rays decreases, when
If the cathode-anode potential difference in an X-ray tube be 10 5 V, then the maximum energy of X-ray photon can be
When a beam of accelerated electrons hits a target, a continuous X-ray spectrum is emitted from the target. Which of the following wavelengths is absent in X-ray spectrum, if the X-ray tube is operating at 40,000 volts?
The shortest wavelength of X-rays emitted from an X-ray tube depends on the
The wavelength λ of the K a line of characteristic X-ray spectra varies with atomic number approximately
The minimum wavelength of X-rays produced by electrons accelerated by a potential difference of volts is equal to
The potential difference applied to an X-ray tube is increased. As a result, in the emitted radiaiion
A potential difference of 42,000 volts is used in an X-ray tube to accelerate electrons. The maximum frequency of the X-radiations produced is
Mosley measured the frequency (f) of the characteristic X-rays from many metals of different atomic number (Z) and represented his results by a relation known as Mosley’s law. This law is (a, b are constants)
The graph between the square root of the frequency of a specific line of characteristic spectrum of X-rays and the atomic number of the target will be
The minimum wavelength of the X-rays produced by electrons accelerated through a potential difference of V volts is directly proportional to
For production of characteristic K β X-rays, the electron transition is
If the minimum wavelength obtained in an X-ray tube is 2 . 5 x 10 – 10 m, the operating potential of the tube will be
An X-ray tube with a copper target emits CuK α line of wavelength 1.50 A o . What should be the minimum voltage through which electrons are to be accelerated to produce this wavelength of X rays? h = 6 .63 × 10 − 34 J − sec , c = 3 × 10 8 m / s
Let λ α , λ β and λ α ‘ denote the wavelengths of the X-rays of the K α , K β and L α lines in the characteristic X-rays for a metal
The wavelength of K α line in copper is 1.54 A o . The ionisation energy of K electron in copper in Joule is
The wavelength of K α X-rays produced by an X-ray tube is 0.76 A o . The atomic number of the anode material of the tube is
Electrons with energy 80 keV are incident on the tungsten target of an X-ray tube. K shell electrons of tungsten have ionization energy 72.5 keV. X-rays emitted by the tube contain only
The continuous x-ray spectrum obtained from a Coolidge tube is of the form
The intensity of X-rays from a Coolidge tube is plotted against wavelength as shown in the figure. The minimum wavelength found is λ c and the wavelength of the K α line is λ K . As the accelerating voltage is increased
The figure represents the observed intensity of X-rays emitted by an X-ray tube as a function of wavelength. The sharp peaks A and B denote
The graph that correctly represents the relation of frequency v of a particular characteristic X-ray with the atomic number Z of the material is
The intensity distribution of X-rays from two Coolidge tubes operated on different voltages V 1 and V 2 and using different target materials of atomic numbers Z 1 and Z 2 is shown in the figure. Which one of the following inequalities is true?
For characteristic X-ray of some material
If the potential difference between the anode and cathode of the X-ray tube is increases
K α wavelength emitted by an atom of atomic number Z = 11 is λ . Find the atomic number for an atom that emits K α radiation with wavelength 4 λ .
In a discharge tube ionization of enclosed gas is produced due to collisions between
Hard X-rays for the study of fractures in bones should have a minimum wavelength of 10 – 11 m. The accelerating voltage for electrons in X-ray machine should be
Statement I: X-rays cannot be diffracted by means of grating. Statement II: X-rays does not obey Bragg’s law.
Statement I: Intensity of X-rays can be controlled by adjusting the filament current and voltage. Statement I!: The intensity of X-rays does not depend on number of photons emitted per second from the target.
Statement l: Anode of Coolidge tube gets heated up at time of emission of X-rays. Statement II: The anode of Coolidge tube is made of a material of high melting point.
In the diagram a graph between the intensity of X-rays emitted by a molybdenum target and the wavelength is shown, when electrons of 30 keV are incident on the target. In the graph one peak is of K α line and the other peak is of K β line
Solid targets of different elements are bombarded by highly energetic electron beams. The frequency (f) of the . characteristic X-rays emitted from different targets varies with atomic number Z as
The K α X-rays arising from a cobalt (z : 27) target have a wavelength of 179 pm. The K α X-rays arising from a nickel target (z = 28) is
Energy of the electron in H e + ion is four times the energy of the electron in the first excited state if hydrogen atom. Then orbital angular momentum of the electron in the above said H e + ion is
What is the longest wavelength of singly ionized Helium atom in the ground state, that it will absorb strongly?
The magnitude energy of electron of hydrogen atom in a stationary orbit of radius r n is proportional to
If de Broglie wavelength of electron in the ground state of hydrogen atom is λ , what will be the de Broglie wavelength of the electron in H e + when the ion is in the second excited state?
Ratio of shortest wavelength of Balmer series in a hydrogen atom to that of Lymann series in a H e + ion is
If the electron in an hydrogen atom jumps from an orbit with level n i = 3 to an orbit with level n f = 2, the emitted radiation has a wavelength given by
What would be the radius of second orbit of He + ion?
The transition from the state n = 4 to n =3 in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from :
The radius of the first permitted Bohr orbit for the electron, in a hydrogen atom equals 0.51 Å and its ground state energy equals –13.6 eV. if the electron in the hydrogen atom is replaced by muon ( μ – ) [charge same as electron and mass 207 m e ], the first Bohr radius and ground state energy will be :
The energy of an electron in an excited hydrogen atom is –3.4 eV. Then, according to Bohr’s Theory, the angular momentum of this electron, in Js, in
The radius of the Bohr orbit in the ground state of hydrogen atom is 0.5 A 0 . The radius of the orbit of the electron in the third excited state of He + will be
As the electron in Bohr orbit of hydrogen atom passes from state n = 2 to n = 1, the KE (K) and PE (U) change as :
The electron in a hydrogen atom makes a transition from n = n 1 to n = n 2 state. The time period of the electron in the initial state is eight times that in the final state. The possible values of n 1 and n 2 are
Orbits of a particle moving in a circle are such that the perimeter of the orbit equals an integer number of de-Broglie wavelengths of the particle. For a charged particle moving in a plane perpendicular to a magnetic field, the radius of the nth orbital will therefore be proportional to
Consider 3 rd orbit of He + (Helium) Using non relativistic approach, the speed of electron in this orbit will be (given K = 9 × 10 9 constant, Z = 2 and h= 6.6×10 -34 Js) (Plancks constant=h)
What is the potential energy of the electron in the first excited state of hydrogen atom?
The energy of characteristic X-ray is a consequence of which of the following?
Wavelength of emission from Hydrogen atom when electron jumps from fourth orbit to ground state is λ . What is the wavelength of emission coming from He + ion when electron jumps from third orbit to ground state is
In Bohr model of hydrogen atom, magnitude of force acting on the electron in the ground state of hydrogen atom is F. Then the magnitude of force acting on the electron of He + ion in the second excited state is
If energy and angular momentum of electron in the ground state of hydrogen atom E 0 and L 0 respectively, then in a He + ion, energy of the electron whose angular momentum is 3L 0 , will be
Ratio of minimum frequency of lymann series to the maximum frequency of Balmer series is
Which of the following cannot be the energy of the electron in the hydrogen atom?
If speed of electron in the ground state of hydrogen atom is 2.2 × 10 6 m / s , which of the following cannot be the speed of electron in any orbit of He + ion?
When a photon of Lymann series, emitted from hydrogen atom falls on the metal surface of a photo electric cell having work function 6.044 eV. The maximum kinetic energy of the photoelectron is found to be 6.022 eV. The wavelength of radiation emitted from hydrogen atom belongs to
If ω 0 be the orbital angular velocity of electron in the ground state of hydrogen atom, then which of the following may be the angular velocity of electron in any orbit in Li ++ ion?
Which of the following is true?
The minimum energy required to take out the only electron from the ground state of Li ++ is
According to Bohr’s principle, the relation between the principal quantum number (n) and the radius of the orbit (r) is
If first excitation potential of hydrogen – like atom is V electron volt, then the ionization energy of this atom will be
How much work must be done to pull apart the electron and the proton that make up the hydrogen atom, if the atom is initially in the state n = 2?
In Li +2 ion, find the angular momentum of the electron, if it is in the first orbit:
A hydrogen atom is in an excited state of principle quantum number n. It emits a photon of wavelength λ when it returns to the ground state. The value of n is
When hydrogen atom absorbs a photon of wavelength 60 nm, photo-ionization of atom occurs. The maximum kinetic energy of emitted electron will be
Which of the following types of radiation is not emitted by electronic structure of atoms
According to Bohr’s postulates, which of the following quantities takes discrete values
The angular speed of the electron in the ne orbit of Bohr hydrogen atom is
An electron in hydrogen and one in a singly ionised helium atom are excited to the state n = 2. A photon is emitted when these electrons iump back to the ground state in each case. Then
The limit of Balmer series is 8646 Å The wavelength of the first member of this series will be
In the following energy level diagram, when an atom makes transition from 2 E energy level to E energy level, then it emits a photon of wavelength L The wavelength corresponding to transition from 4 E / 3 energy level to E energy level will be
If the wavelengths of the first line of the Lyman series for the hydrogen atom is 1210 Å then the wavelength of the first line of the Balmer series of the hydrogen spectrum is
The wavelengths of the first line in Balmer series in hydrogen spectrum is λ What is the wavelength of second line
An electron jumps from the 4 th orbit to 2 nd orbit of hydrogen atom. Given the Rydberg’s constant R = 10 7 m − 1 the frequency in Hz of there emitted radiation will be
Of the following transitions in hydrogen atom, the one which gives an absorption line of highest frequency is
The frequency of the first line of Balmer series in hydrogen atom is v 0 Hz. The frequency v of the line emitted by a single ionized helium atom is
