PhysicsPhysics QuestionsOptics Questions for CBSE Class 12th

Optics Questions for CBSE Class 12th

If a ray of light is incident on a plane mirror ( placed along X axis ) and the unit vector of the incident ray is given by i ^ 2 – j ^ 2 , then find the angle of reflection

As the object moves from infinity to focus, then which is true, about the image formed by a single a concave mirror?

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    Light enters at an angle of incidence in a transparent rod, through one end. Refractive index of the material of the rod is ‘ μ ‘ The light once entered into it will not leave it through its lateral face, whatsoever be the value of angle of incidence, if

    A lens forms a diminished and erect image of an object. The magnification is 1 / 4. Then the ratio of object distance to focal length is

    A ray of light is incident at a glass-water interface at an angle of incidence 37 0 . The ray finally emerges from water surface parallel to the surface of water. Then refractive index of glass is tan 37 0 = 3 4 , μ w = 4 3

    Coming from vacuum, a ray of light in incident on a slab of glass of refractive index 3 such that the angle of incidence is twice the angle of deviation. Refraction is at only one surface. Then the angle of deviation is

    What happens to the frequency and the wavelength when light passes from a rarer to a denser medium?

    If the critical angle for total internal reflection from a medium to vacuum is 45°, then velocity of light in the medium is,

    A compound microscope has two convex lens system with focal lengths 2cm and 5cm. An object is 2.5cm away from the objective lens. The tube length of microscope when magnification is maximum is equal to

    A ray of light falls on the surface of a spherical glass paper weight making an angle α with the normal and is refracted in the glass medium at an angle β . The angle of deviation of the emergent ray from the direction of incident ray is

    A beam of light propagates through a medium 1 and falls onto another medium 2, at an angle α 1 as shown in Fig. After that, it propagates in medium 2 at an angle α 2 as shown. The light’s wavelength in medium 1 is λ 1 . What is the wavelength of light in medium2?

    A luminous point is moving at speed v 0 towards a spherical mirror, along its axis. Then the speed at which the image of this point object is moving is given by (with R = radius of curvature and u = object distance)

    In a terrestrial telescope the focal length of erecting lens is 2 cm. The length of the telescope is 96 cm. If the magnifying power of the telescope is 10, then the focal lengths of eye piece and objective are respectively

    Distance of a bird from a fish, as observed by a fish is x. and distance of the fish from the bird as observed by the bird is y. Then refractive index of water is

    Two plane mirrors are at 45 o to each other. If an object is placed between them, then the number of images will be

    With a concave mirror, an object is placed at a distance x 1 from the principal focus, on the principal axis. The image is formed at a distance x 2 from the principal focus. The focal length of the mirror is

    You are asked to design a shaving mirror assuming that a person keeps it 10cm from his face and views the magnified image of the face at the closest comfortable distance of 25cm. The radius of curvature of the mirror would then be :

    A ray of light refracts from medium 1 into a thin layer of medium 2, crosses the layer and is incident at the critical angle on the interface between the medium 2 and 3 as shown in the figure. If the angle of incidence of ray is θ , the value of θ is :

    The angle of minimum deviation by prism is (180°–2A). Its critical angle will be

    A certain person has a minimum distance of distinct vision of 150cm. He wishes to read at a distance of 25cm. What focal length glasses should he use?

    The effective focal length of the lens combination shown in figure is – 60 cm. The radii of curvature of the curved surfaces of the plano– convex lenses are 12 cm each and refractive index of the material of the lens is 1.5. The refractive index of the liquid is

    A ray of light is incident on a glass sphere of refractive index 3/2. What should be the angle of incidence so that the ray which enters the sphere does not come out of the sphere ?

    A wire mesh consisting of very small squares is viewed at a distance of 8cm through a magnifying converging lens of focal length 10cm, kept close to the eye. The magnification produced by the lens is

    Find the wrong statement.

    When a glass prism of refracting angle 60 o is immersed in a liquid its angle of minimum deviation is 30 o . The critical angle of glass with respect to the liquid medium is

    According to the thin lens formula, which one of the following is true regarding the focal length of the lens?

    In an astronomical telescope in normal adjustment, straight black line of length L is drawn on the objective. The eye piece forms a real image of this line. The length of this image is l. The magnification of the telescope is

    An object is placed at a distance of 40cm from a concave mirror of focal length 15cm. If the object is displaced through a distance of 20cm towards the mirror, the displacement of the image will be

    The Cauchy’s formula is

    A vertical ray of light strikes the reflecting surface of a plane mirror which is inclined to the horizontal at an angle of 45 o as shown in figure. If the mirror rotates anticlockwise through an angle of 15 o , then the angle of deviation of the reflected ray is

    Two convex lenses, each of focal length 40 cm, are filled at the ends of a tube and the tube is filled with water μ = 4 3 . A beam of parallel rays parallel to the axis of the tube, enters the tube through one end and emerges from the tube as a beam of parallel rays of same diameter as the incident beam. If refractive index of glass is 1.5, find the length l of the tube.

    A particle is moving along x-axis with 4 m/sec in-front of plane mirror, which is moving along negative direction with 2 m/sec. speed of image with respect to ground will be

    An astronomical telescope has objective and eyepiece of focal lengths 40 c m and 4 c m respectively. To view an object 200 c m away from the objective, the lenses must be separated by a distance

    A compound microscope has a magnifying power of 100 when the image is formed at infinity. The objective has a focal length of 0.5 cm and the tube length is 6.5 cm. Find the focal length of the eye- piece

    A ray of light is incident at an angle of 60 o on one face of a prism of angle 30 o . The ray emerging out of the prism makes an angle of 30 o with the incident ray. The emergent ray is

    If the focal length of objective lens is increased then magnifying power of

    The angle of incidence for a ray of light at a refracting surface of a prism is 45 0 . The angle of prism is 60 0 . If the ray suffers minimum deviation through the prism, the angle of minimum deviation and refractive index of the material of the prism respectively, are

    An equilateral prism ABC is placed in air with its base side BC lying horizontally along x-axis. A light ray 3 z + x = 10 is incident at a point P on face AB of the prism. If μ for the prism is 3 2 , then net deviation of the ray as it emerges out of the prism is

    Pick the wrong answer in the context with rainbow.

    The maximum magnifying power of a simple microscope is obtained when the object is placed

    Two plane mirrors are inclined at 70 o . A ray incident on one mirror at angle, θ after reflection falls on second mirror and is reflected from there parallel to first mirror. The value of θ is

    In the figure shown, the image of a real object O is formed at point I. AB is the principal axis of the mirror, the mirror must be:

    A person has near point at 60 cm. The focal length of spectacle lenses to read at 22 cm having glasses separated 2 cm from the eyes, is :

    In a compound microscope, the length of microscope is 21.5 cm, the focal length of the objective is 1.6 cm, the focal length of the eye piece is 2.1 cm and if final image is formed at infinity. Then the distance of the object from the objective lens is

    A fish looks upward at an unobstructed overcast sky. What total angle does the sky appear to subtend? (Take refractive index of water as 2 ).

    Two convex lenses placed in contact form the image of a distant object at P. If the lens B is moved to the right, the image will

    A given equiconvex lens is cut into four parts and the parts are rearranged as shown. If the initial focal length is f, then after rearrangement the equivalent focal length is

    Two plane mirrors are inclined at same angle θ as shown in figure. A ray of light parallel to M 2 is incident on M 1 . After two successive reflections at the mirrors, the emergent ray becomes parallel to the mirror M 1 . Then the total angle of deviation of the ray is

    A thin prism P 1 with angle 3 0 is made of glass of refractive index 1.52 is combined with another prism P 2 made of glass of refractive index 1.65 to produce direct vision combination. The angle of prism P 2 is

    A ray of light is incident on a transparent slab of glass having refractive index 3 . A part of incident energy is reflected and the balance amount of energy is refracted into the slab. If the angle between refracted and reflected rays is 90 o , what is the angle of deviation of the reflected ray?

    For a prism kept in air, it is observed that for an angle of incidence 60 o , the angle of prism A, The angle of emergence e and the angle of deviation δ become equal. If refractive index of the prism is 3 , angle of prism A is

    When a parallel beam of white light passes through a convex lens, red, yellow and violet colours are focussed at 20.5 cm, 20 cm and 19.5 cm respectively. Then dispersive power of material of the lens is

    For crown glass, μ v = 1.523 and μ r = 1.5145 . Dispersive power crown glass is

    Focal length of a convex lens in air is 10 cm. Find its focal length in water. Given μ g = 3 / 2   and   μ w = 4 / 3

    Difference in maximum and minimum magnification of an astronomical telescope is 2.4. Focal length of the objective is

    A screen is placed at 80 cm from an object. The image of the object on the screen is formed by a convex lens at two different location separated by 20 cm. Focal length of lens is

    The difference in maximum and minimum magnification of an astronomical telescope is 2.4 then focal length of the objective is

    In the arrangement shown, f 1 = 20   c m and f 2 = 10   c m . A parallel beam of light is incident on the convex lens. Then find the distance ‘d’ for which the final emergent beam after refraction through the concave lens will become parallel again.

    Refractive indices of two media in contact are 3 and 1.5. A ray of light travelling in optically denser medium strikes the interface at an angle of incidence equal to the critical angle of the pair of media. Then angle of deviation of the refracted ray is

    Focal length of a convex lens made of crown glass is 20 cm. An achromatic lens is to be made by keeping two lenses, one made of crown glass and the other made of flint glass, in contact with each other. If dispersive power of crown glass is 0.016 and that of flint glass is 0.03, find the focal length of the lens made of flint glass.

    A point source of light is placed at the bottom of a water lake. If the area of the illuminated circle on the surface is equal to 3 times the square of the depth of the lake. The refractive index of water is

    An object is placed at 20cm from a convex mirror of focal length 10 cm. The image formed by a mirror is

    A ray of light from a denser medium strikes a rarer medium. The reflected and refracted rays make an angle of 90 o with each other. The angles of reflection and refraction are r and r I . The critical angle would be

    The focal length of a convex lens of refractive index 1.5 is ‘f’ when it is placed in air. When it is immersed in a liquid it behaves as a converging lens and its focal length becomes xf (x > 1). The refractive index of the liquid is

    A lens having focal length f and aperture of diameter d forms an image of intensity I. Aperture of diameter d/2 in central region of lens is covered by a black paper. Focal length of lens and intensity of image now will be respectively

    The focal length of the objective and the eyepiece of a telescope are 50cm and 5cm respectively. If the telescope is focussed for distinct vision on a scale distant 2m from its objective, then its magnifying power will be :

    A light ray from air is incident (as shown in figure) at one end of a glass fiber (refractive index m = 1.5) making an incidence angle of 60 o on the lateral surface, so that it undergoes a total internal reflection. How much time would it take to traverse the straight fiber of length 1 km(nearly)

    An air bubble is a glass slab with refractive index 1.5 (near normal incidence) is 5 cm deep when viewed from one surface and 3 cm deep when viewed from the opposite face. The thickness (in cm) of the slab is

    Diameter of a plano – convex lens is 6 cm and its thickness at the centre is 3 mm. Then the focal length of the lens, if the speed of light in the material of lens is 2 × 10 8 m/s

    A person can see things clearly upto 3m what is the power of lens he should use so that he can see upto 12 m ?

    In a compound microscope, the focal lengths of two lenses are 1.5 cm and 6.25 cm. An object is placed at 2 cm from objective and the final image is formed at 25 cm from the eye lens. The distance between the two lenses is (in cm)

    A thin prism having refracting angle 10° is made glass of refractive index 1.42. This prism is combined with another thin prism of glass of refractive index 1.7. This combination produces dispersion without deviation. The refracting angle of second prism should be :

    An astronomical telescope has an angular magnification of magnitude 5 for distant objects. The seperation between the objective and the eye piece is 36 cm and the final image is formed at infinity. The focal length f 0 of the objective and the focal length f e of the eye piece are

    The magnifying power of an astronomical telescope for normal vision is 7 and its tube length is 1.6 m. Then focal lengths of eye piece and objective are

    In the diagram shown, a plot between δ (angle of deviation) versus i (angle of incidence) for a triangular prism is given. From the observed plot, some conclusion can be drawn. Mark out the correct conclusion.

    How much intensity of the image is increased if the diameter of the objective of a telescope is doubled?

    The optical path of monochromatic light is the same if it travels 2 cm thickness of glass or 2.25 cm thickness of water. If the refractive index of water is 1.33, what is the refractive index of glass?

    A lens immersed in a transparent liquid is not visible. Under what condition can this happen?

    ABCD is a composite slab made of two slabs of transparent materials having refractive indices μ 1 = 4 3 and μ 2 = 3 2 . P is a small object. For near normal vision from top of the composite slab, the apparent position of the object P i.e. at the interface of the slabs. Then the ratio t 1 t 2 is

    A 4 3 cm diameter beam of light is incident on the surface of a transparent sphere of radius 4  cm as shown in figure. If the beam converges at point B as shown in figure, the refractive index of the material of the sphere is

    A convex lens is at a distance of 10 cm from a convex mirror of focal length 10 cm as shown in figure. A beam of light parallel to the principal axis is incident on the tens. After refraction through the lens, reflection at the mirror and again refraction through the lens, the final emergent beam refraces the path of the incident beam then focal length of the lens is

    A man stands in front of a mirror of special shape. He finds that his image has a very small head, a fat body, and legs of normal size. What can we say about the shapes of the three parts of the mirror?

    The plane surface of a plano convex lens having radius of curvature 20 cm is silvered. If this silvered lens is equivalent to a concave mirror, the radius of curvature of the mirror is (Refractive index of glass is 1.5)

    Find the wrong statement for a convex lens for a real object

    A fish looking up through the water sees the outside world, constant in a circular horizon. If the refractive index of water is 4 3 and the fish is 12 cm below the water surface, the radius of this circle in cm is:

    A lens of glass is immersed in water. What will be its effect on the power of the lens ? Power will:

    For the arrangement shown in figure what is the distance between the first image formed at M1 and the second image formed at M2 ?

    A ray of light falls on a transparent glass sphere of refractive index μ . The ray emerges from the sphere parallel to the line AB . So, μ =

    If a person can sees clearly at a distance of 100 cm, then find the power of lens used to see object at 40 cm,

    A short linear object of length b lies along the axis of a concave mirror of focal length f at a distance u from the pole of the mirror, what is the size of image?

    A ray of light falls on the surface of a spherical paper weight making an angle α with the normal and is refracted in the medium at an angle β . The angle of deviation of the emergent ray from the direction of the incident ray is

    The refractive index of the material of a prism is 2 and the angle of the prism is 30 o . One of the two refracting surfaces of the prism is made a mirror inwards, by silver coating. A beam of monochromatic light entering the prism from the other face will retrace its path (after reflection from the silvered surface) if its angle of incidence on the prism is

    An object is placed at a distance of 40cm from a concave mirror of focal length 15cm. If the object is displaced through a distance of 20cm towards the mirror, the displacement of the image will be

    Match the corresponding entries of column 1 with column 2.[Where m is the magnification produced by the mirror]

    An equiconvex lens of focal length 10cm (at t=0) and refractive index (1.5) is placed in a medium whose refractive index varies with time as μ = 1 + t 10 ; t in seconds. The value of t when the lens acts as a diverging lens of focal length 20cm is

    An equilateral prism ABC is placed in air with its base side BC lying horizontally along x-axis. A light ray 3 z + x = 10 is incident at a point P on face AB of the prism. The value of μ of prism for which the ray grazes the face AC is

    Which statement is correct ?

    An astronomical refracting telescope will have large angular magnification and high angular resolution, when it has an obiective lens of

    The angle of a prism is A. One of its refracting surfaces is silvered. Light rays falling at an angle of incidence 2A on the first surface returns back through the same path after suffering reflection at the silvered surface. The refractive index μ , of the prism is

    A beam of light consisting of red, green and blue colours is incident on a right angled prism. The refractive index of the material of the prism for the above red, green and blue wavelengths are 1.39, 1.44 and 1.47 respectively. The prism will be

    In total internal reflection when the angle of incidence is equal to the critical angle for the pair of media in contact, what will be angle of refraction?

    Two similar thin equi-convex lenses, of focal length f each, are kept coaxially in contact with each other such that the focal length of the combination is F 1 . When the space between the two lenses is filled with glycerin (which has the same refractive index ( μ = 1 . 5 ) as that of glass) then the equivalent focal length is F 2 . The ratio F 1 : F 2 will be

    For the given incident ray as shown in figure, the condition of total internal reflection of the ray will be satisfied if the refractive index of block will be

    Minimum magnifying power of an astronomical telescope is 20. If the focal length of the eyepiece is 5 cm, then distance between the objective and eyepiece is

    The angular resolution of a 10 cm diameter telescope at a wavelength of 5000 Å is of the order of :

    A bird in air looks at a fish directly below it inside in a transparent liquid in a tank. If the distance of the fish as estimated by the bird is h1 and that of the bird as estimated by the fish is h2, then the refractive index of liquid is

    In an astronomical telescope in normal adjustment a straight black line of length L is drawn on inside part of objective lens. The eye-piece forms a real image of this line. The length of this image is I. The magnification of the telescope is

    A piano convex lens fits exactly into a piano concave lens. Their plane surfaces are parallel to each other. If lenses are made of different materials of refractive indices μ 1 and μ 2 and R is the radius of curvature of the curved surface of the lenses, then the focal length of the combination is

    For a normal eye, the cornea of eye provides a converging power of 40 D and the least converging power of the eye lens behind the cornea is 20 D. Using this information, the distance between the retina and the cornea-eye lens can be estimated to be

    An incident ray of light is falling on a plane mirror and getting reflected on a screen. If the mirror is now rotated with angular speed 20 rad/sec by keeping the incident ray fixed, then at what angular speed the reflected ray would be rotating?

    A convex lens is dipped in a liquid whose refractive index is equal to the refractive index of the lens. Then its focal length will

    A ray of light through four transparent media with refractive indices μ 1 , μ 2 , μ 3 , a n d μ 4 , is shown in fig. The surfaces of all media are parallel. If the emergent ray CD is parallel to the incident ray AB, we must have

    Two identical thin plano-convex glass lenses (refractive index 1.5) each having radius of curvature of 20 cm are placed with their convex surfaces in contact at the centre. The intervening space is filled with oil of refractive index 1.7 . The focal length of the combination is

    Two identical glass μ g = 3 2 equiconvex lenses of focal length f each are kept in contact. The space between the two lenses is filled with water μ w = 4 3 . The focal length of the combination is

    The refracting angle of a prism is A, and refractive index of the material of the prism is cot (A / 2). The angle of minimum deviation is

    An air bubble in a glass slab with refractive index 1.5 (near normal incidence) is 5cm deep when viewed from one surface and 3cm deep when viewed from the opposite face. The thickness (in cm ) of the slab is

    A person can see clearly objects only when they lie between 50 cm and 400 cm from his eyes. In order to increase the maximum distance of distinct vision to infinity, the type and power of the correcting lens, the person has to use, will be

    The reddish appearance of the sun at sunrise and sunset is due to

    An equilateral prism ABC is placed in air with its base side BC lying horizontally along x-axis. A light ray 3 z + x = 10 is incident at a point P on face AB of the prism. If the face BC is silvered then net deviation of the finally emerging ray with respect to the incident ray on prism is ( μ of the prism is 3 2 )

    The radius of curvature of curved surface of a thin plano – convex lens is 10 cm and the refractive index is 1.5. If the plane surface is silvered, then the focal length will be

    For the angle of minimum deviation of a prism to be equal to its refracting angle, the prism must be made of a material whose refractive index :

    The angular resolution of a telescope having diameter of 12.2 cm with a wavelength of 6000 Å is of the order of

    A beam of light from a source L is incident normally on a plane mirror fixed at a certain distance x from the source. The beam is reflected back as a spot on a scale placed just above the source L. When the mirror is rotated through a small angle θ the spot of the light is found to move through a distance y on the scale. The angle θ is given by

    A thin prism having refracting angle 10° is made of glass of refractive index 1.42. This prism is combined with another thin prism of glass of refractive index 1.7 . This combination produces dispersion without deviation. The refracting angle of second prism should be

    A ray is incident at an angle of incidence i on one surface of a small angle prism (with angle of prism A) and emerges normally from the opposite surface. If the refractive index of the material of the prism is μ then the angle of incidence is nearly equal to :

    Assume that light of wavelenght 600 nm is coming from a star. The limit of resolution of telescope whose objective has a diameter of 2 m is :

    When a uranium isotope 92 235 U is bombarded with a neutron, it generate 36 89 Kr , three neutrons and :

    An object is placed on the principal axis of a concave mirror at a distance of 1.5 f (f is the focal length). The image will be at,

    The power of a biconvex lens is 10 dioptre and the radius of curvature of each surface is 10 cm. Then the refractive index of the material of the lens is,

    Two converging lenses are placed 20.0 cm apart, as shown in figure. If the first lens has a focal length of 10.0 cm and the second has a focal length of 20.0 cm, locate the final image formed of an object 30.0 cm in front of the first lens.

    A thin prism P 1 with angle 4 o made from glass of refractive index 1.54 is combined with another thin prism P 2 made from glass of refractive index 1.72 to produce dispersion without deviation. The angle of the prism P 2 is

    Two point objects are placed on principal axis of a thin converging lens. One is 20 cm from the lens and other is on the other side of lens at a distance of 40 cm from the lens. The images of both objects coincide. The magnitude of focal length of lens is

    A fish at a depth of 12 cm in water is viewed by an observer on the bank of a lake. Through what height is the image of fish raised ? ( μ = 4 / 3)

    An astronomical telescope has an angular magnification of magnitude 5 for distant objects. The separation between the objective and the eye-piece is 36 cm and the final image is formed at infinity. The focal length f 0 of the objective and f e of the eye-piece are :

    For an angle of incidence θ on an equilateral prism of refractive index 3 the ray refracted is parallel to the base inside the prism. The value of θ is

    Two plane mirrors are joined together as shown in figure. Two point objects O 1 and O 2 are placed symmetrically such that A O 1 = A O 2 . The image of the two objects is common if :

    A motor car is fitted with a convex driving mirror of focal length 20 cm. A second motor car 2.01 m broad and 1.005m high is 40 m behind the first car. The size of the image of the second car seen in the mirror of the first, is.

    An equiconvex lens has power P. It is cut into two symmetrical halves by a plane containing the principal axis. The power of one part will be,

    A double convex lens has focal length 25 cm. The radius of curvature of one of the surfaces is double of the other. Find the radii if the refractive index of the material of the lens is 1.5.

    If the angle of a prism is 60° and angle of minimum deviation is 40°, then the angle of refraction will be:

    A light beam is incident on a denser medium whose refractive index is 1.414 at an angle of incidence 45°. Find the ratio of width of refracted beam in a medium to the width of the incident beam in air.

    The graph shows how the inverse of magnification 1 m produced by a thin convex lens varies with object distance u. What was the focal length of the lens used?

    A stationary swimmer is inside a liquid of refractive index n 1 is at a distance ‘d’ from a fixed point P inside the liquid. A rectangular block of Thickness ‘t’ and refractive index n 2 n 2    <     n 1 is now placed between S and P. Now S will observe P to be at a distance

    The focal length of the objective of a terrestrial telescope is 80 cm and it is adjusted for normal vision to produce a magnification of 20. If the focal length of erecting lens is 20cm, then full length of telescope tube will be

    A glass prism has angle of prism 90 O and a refractive index of 1.5. A ray is incident at an angle of 30 O . The ray emerges from an adjacent face at an angle of

    Two plane mirrors OM 1 and OM 2 are inclined to each other such that angle between them is ‘A’. A beam of parallel rays are incident on them as shown in figure. Then the angle between the reflected rays is

    Considering near normal incidence of ray, the equivalent refractive index of combination of two slabs shown in figure is

    A simple microscope consists of a concave lens of power –10D and a convex lens of power +20D in contact. If the image is formed at infinity, then the magnifying power is (D = 25 cm)

    The two lenses shown are illuminated by a beam of parallel rays of light from left. Lens B is then moved slowly towards lens A. The beam emerging from lens B is,

    Magnification produced by an astronomical telescope for normal vision is 20. Length of the telescope tube for normal vision is 105cm. Then focal length of the objective is

    A person cannot see objects beyond 2.0 m clearly. If he wants to see the distant objects clearly, the power of lens required to correct his defective vision will be

    A thin prism P 1 with angle 4 0 made from glass of refractive index 1.54 is combined with another thin prism P 2 made from glass of refractive index 1.72 to produce dispersion without deviation. The angle of the prism P 2 is

    A fish is vertically below a flying bird moving vertically down toward water surface. The bird will appear to the fish to be

    A point object is placed at a distance of 25 cm from a convex lens of focal length 20 cm. If a glass slab of thickness t and refractive index 1.5 is inserted between the lens and the object, the image is formed at infinity. The thickness t is

    The velocity of light in a medium is half its velocity in air. If a ray of light emerges from such a medium into air, the angle of incidence, at which it will be totally internally reflected, is

    A diver in a swimming pool wants to signal his distress to a person lying on the edge of the pool by flashing his water proof flash light

    A man can see the objects upto a distance of one metre from his eyes. For correcting his eye sight so that he can see an object at infinity, he requires a lens whose power is

    Two point sources S 1 and S 2 are 24cm apart where should a convex lens of focal length 9 cm be placed in between them so that the images of both sources are formed at the same place

    A ray of light falls at angle of incidence 60° on one face of prism of angle 30°. Emerging ray makes an angle of 30° with incident ray. The refractive index of material of prism is

    A fish at a depth of 12 cm in water is viewed by an observer on the bank of a lake. Through what height is the image of fish raised ? ( μ = 4 / 3)

    The speed of light in media M 1 and M 2 is 1 . 5 x 10 8 m / s and 2 x 10 8 m / s respectively. A ray of light enters from medium M 1 to M 2 at an incidence angle i . If the ray suffers total internal reflection, the value of i is :

    The refractive index of the material of a prism is 2 and its refracting angle is 30 0 . One of the refracting surfaces of the prism is made a mirror inwards. A beam of monochromatic light entering the prism from the other face retraces its path, after reflection from mirrored surface, if its angle of incidence on prism is

    A circular beam of light of diameter d = 2 cm falls on a plane surface of glass. The angle of incidence is 60° and refractive index of glass is μ = 3/2. The diameter of the refracted beam is

    In an electron microscope, the accelerating voltage is increased from 20 kV to 80 kV. If resolving power of 20 KV is R, the resolving power for 80 KV is

    A thin equiconvex lens is placed on a plane mirror as shown in figure. A point object O is placed on the principal axis of the lens at a distance of 20 cm from the lens. It is observed that after refraction through the lens, reflection at the mirror and again refraction through the lens, the final image coincides with the object. If radius of curvature of the curved surfaces of the lens is 20 cm, refractive index of its material is

    A glass prism has refracting angle 90 0 . If angle of minimum deviation is 30 0 , refractive index of the material of the prism is

    The diameter of the moon is 3.5    ×   10 3    k m and its distance from earth is 3.8    ×   10 5    k m . When seen by a telescope having focal lengths of the objective and the eye piece as 40 mm and 10 mm respectively, the angle subtended by the image of the moon at the eyes for normal vision will be approximately

    Focal lengths of the objective and eye piece of an astronomical telescope are 50 cm and 5 cm respectively. The least distance of distinct vision is 25 cm. The telescope is focussed on a distant star for distinct vision. The separation between and eye piece will be

    A ray of light is incident on a plane mirror, along the direction given by vector 2 i ^ − 3 j ^ + 4 k ^ . Find the unit vector along reflected ray. Take normal to mirror along the direction of vector 3 i ^ − 6 j ^ + 2 k ^ .

    A screen is placed at 80 cm from an object. The image of the object on the screen is formed by a convex lens at two different location separated by 20 cm. Focal length of lens in cm is

    A ray of light is incident upon a parallel sided transparent slab of thickness 9 cm at an angle of incidence 60 0 . If the angle of refraction is 30 0 , the lateral displacement of the light ray is

    Refractive index of the material of a prism is 3 and refracting angle of the prism is 60 o . Then the minimum deviation is

    Magnification of an astronomical telescope is 4 for normal vision and its tube length for normal vision is 1m. What will be the tube length if the final image is formed at least distance for distinct vision (25 cm)?

    A ray of light strikes the refracting surface of a thin prism having refracting angle 4 o at near normal incidence. If angle of deviation is 2 o , refractive index of the material of the prism is

    A thin prism having refracting angle 4 o is made of a transparent material whose refractive index for violet light is 1.6 and that for red light is 1.4. Then dispersive power of the material of the prism is

    A linear object of height 5 mm is placed on the principal axis of a concave lens of focal length 20 cm at a distance of 20 cm from the lens and the object is perpendicular to the principal axis. Then size of its image is

    The radii of curvatures of convex surface, concave surface of a concavo-convex lens are in the ratio 1 : 2. The refractive index of the material of lens is 5/4 and its focal length is 40 cm. This lens is cut into a plano-convex lens and plano-concave lens. If the plano convex lens is immersed in water then its focal length is

    The absolute refractive indices of diamond and crown glass are 5/2 and 3/2 respectively. What is the critical angle between diamond and crown glass.

    A near sighted person cannot see objects clearly that are beyond 50 cm from his eye. Determine the power of the glasses that will enable him to see distant objects clearly.

    What is the total angle subtended by sky at the eyes of a fish in water? Take refractive index of water as 2

    A converging beam of light converges towards a point 20 cm behind an equiconvex lens placed in the path of the beam. After refraction through the lens, the beam converges at a distance of 10 cm from the lens. If refractive index of glass is 1.5, find the radius of curvature of the curved surfaces of the lens.

    Two convex lenses of focal lengths 20 cm and 30 cm are kept at a separation of 15 cm. Then power of the combination is

    A 12 cm thick slab of a transparent material contains same number of waves 10 cm thick slab of glass having refractive index 1.5 when both are traversed normally by the same monochromatic light. Then the refractive index of the transparent material is

    A person can see clearly only upto a distance of 30 cm. He wants to read a book placed at a distance of 50 cm from his eyes. What is the power of the lens he requires for his spectacles?

    A ray of light incident on one refracting face of a prism of angle 75 0 . It undergoes total internal reflection at the second face. If μ = 2 , the maximum angle of incidence on the first face is

    Primary rainbow is formed due to

    A small object is placed 10 cm infront of a plane mirror. If you stand behind the object 30 cm from the mirror and look at its image, the distance focused for your eye will be

    A person standing in the centre of a room, 12 m high looks into a plane mirror fixed on the wall. Then the minimum length of the plane mirror for him to see the full length image of the wall behind him, is equal to

    If the refractive index of diamond is 2.4 find the velocity of light in diamond. (c = 3×10 8 m/s)

    A monochromatic light passes through a glass slab ( μ = 1.5) of thickness 9 cm in time t 1 . If it takes a time t 2 to travel the same distance through water ( μ = 4 /3) . The value of (t 1 – t 2 ) is

    A ray of light is incident at an angle of 60 o on a 3 cm thick plate ( μ = 3 ) . The shift in the path of the ray as it emerges out from the plate is (in cm)

    A transparent solid cylindrical rod has a refractive index of 2 3 . It is surrounded by air. A light ray is incident at the midpoint of one end of the rod as shown in the figure. The incident angle θ for which the light ray grazes along the wall of the rod is

    A double convex lens of refractive index 1.5 has radii of 20 cm. Incident rays of light parallel to the axis will come to converge at a distance from the lens is

    A glass prism deviates the red and blue rays through 10 o and 12 o respectively. A second prism of equal angle deviates them through 8 o and 10 o respectively. Their dispersive powers are in the ratio

    A microscope consists of two convex lenses of focal lengths 2.0 cm and 6.25 cm placed 15.0 cm apart. Where must the object be placed so that the final virtual image is at a distance of 25 cm from the eye?

    A car is fitted with a convex side -view mirror of focal length 20cm. A second car 2.8m behind the first car is overtaking the first car at relative speed of 15m/s. The speed of the image of the second car as seen in the mirror of the first one is

    At what distance from a convex mirror of focal length 2.5 m should a boy stand so that his image has a height equal to half the original height ?

    An object is placed infront of a concave mirror of focal length ‘f’. A virtual image is formed with a magnification of 2. To obtain a real image of same magnification, the object has to moved by a distance

    A spherical surface of radius of curvature R, separates air (refractive index 1.0) from glass (refractive index 1.5). The centre of curvature is in the glass. A point object P placed in air is found to have a real image Q in the glass. The line PQ cuts the surface at a point O and PO = OQ. The distance PO is equal to

    A plano convex lens fits exactly into a plano concave lens. Their plane surfaces are parallel to each other. If the lenses are made of different materials of refractive indices μ 1 and μ 2 and ‘R’ is the radius of curvature of the curved surfaces of the lenses then the focal length of the combination is

    An eye specialist prescribes spectacles having a combination of a convex lens of focal length 40 cm in contact with a concave lens of focal length 25 cm. The power of this lens combination is

    Image of an object at infinity is formed by a convex lens of focal length 30 cm such that the size of the image is 2 cm. If a concave lens of focal length 20 cm is placed in between the convex lens and the image, at a distance 26 cm from the convex lens, size of the new image is

    An optician while testing the eyes finds the vision of a patient to be 6/12. By this means that

    If the focal length of objective and eye lens are 1.2 cm and 3 cm respectively and the object is put 1.25 cm away from the objective lens and the final image is formed at infinity. The magnifying power of the microscope is

    A astronomical telescope has objective and eyepiece of focal lengths 40 cm and 4 cm respectively. To view an object 200 cm away from the objective, the lenses must be separated by a distance

    The focal length of the eye piece of an astronomical telescope is 5cm and its magnification for normal vision is 10. If the final image is formed at the least distance of distinct vision (25 cm), find the magnification

    The glass prism in Telescope produces

    If i ^ denotes a unit vector along an incident ray, r ^ a unit vector along the refracted ray into a medium of refractive index ‘ μ ‘ and n ^ a unit vector normal to the boundary of the media directed towards the incident medium, then the law of refraction can be written as

    ‘X’ is an optical illusion observed in deserts or over hot extended surfaces like a coal-tarred road, due to which a traveler sees a shimmering pond of water some distance ahead of him and in which the surrounding objects like trees appear inverted. Identify X.

    A fly is sitting on the objective of a telescope. What will be its effect on the final image of the distant object?

    A concave mirror is held in water. What should be the change in the focal length of the mirror?

    A man stands in front of a mirror of special shape. He finds that his image has a very small head, a fat body, and legs of normal size. What can we say about the shapes of the three parts of the mirror?

    The power of a lens whose focal length is 25 cm is:

    The distance of a real object from the focus of a convex mirror of radius of curvature ‘a’ is ‘b’. Then the distance of the image from the focus is

    Identify the principle behind the sparkling of diamonds.

    The magnification produced by ‘X’ is more than unity. Identify X.

    A plane mirror is lying in xy-plane with its reflecting surface facing positive z-axis. A particle is moving towards the reflecting surface of the mirror with velocity 2 i ^ − 2 j ^ − 3 k ^ m / s . If the mirror starts moving with velocity 2 k ^   m / s , velocity of the image of the particle relative to the mirror is

    A ray of red light is incident on the surface of a slab of glass at an angle of incidence of i. The angle of deviation in the slab is found to be δ r . When a ray of violet light is incident on the same slab of glass at same angle of incidence i, the angle of deviation inside the slab is found to be δ . Then

    A concave mirror of focal length f is kept at a distance of 27 cm from a plane mirror. A point object is placed mid way between the mirrors at point O. Rays of light emerging from the object first get reflected by the concave mirror and then by the plane mirror and the final image is formed at the location of the object. Then the value of f is

    A fish is at a depth h below the surface of water μ = 4 3 and a bird is at a height of 2m above the surface of water. The bird and fish are on the same vertical line. If the apparent depth of the fish as viewed by the bird is same as the apparent height of the bird as viewed by the fish, then value of h is

    Two plane mirrors M 1   and   M 2 make an angle of 30 o with each other. A ray of light strikes M 1 at an angle of 45 o as shown in figure. Then after two successive reflections at the mirror, total angle of deviation of the reflected ray will be

    Refractive index of the material of a sphere of radius 10 cm is 2 3 . A point source of light P is placed just inside the surface of the sphere. Then area of the surface of the sphere through which light energy can pass into surrounding air, is

    A glass sphere of radius 10 cm has refractive index μ = 1.5 . A is the position of a point object and B is its image. If A and B are equidistant from the surface of the sphere then separation between A and B is

    ABC is an isosceles right angled triangle with the angle BAC 90 o . A ray of light parallel to the base BC strikes the face AB. The refracted ray in the prism strikes the base BC. If the refractive index of the material of the prism is 2 , find the total angle of deviation of the final emergent ray

    Refractive index of a transparent material for violet light is 1.585 and that for red light is 1.485. A thin prism is made of this material and a ray of white light is incident on one refracting surface of this prism at near normal incidence. Then ratio of angle of dispersion to the mean angle of deviation is

    The refracting angle of a prism, made of a transparent material is 120 o . A ray of light is incident on one refracting surface of the prism. What should be the maximum refracting index of the material of the prism for which the ray of light can pass into the surrounding air through the other refracting surface?

    Two parallel rays, one of red light and the other of violet light, are incident on the flat end of a 2m long glass rod. Wavelength of violet light in vacuum is 4000 A o and that of red light is 7000 A o . The mean refractive index of glass is 1.5 then number of waves of violet light in the rod exceeds the number of waves of red light by

    Number of waves in a length l traversed by a mono chromatic light in vacuum is 10 6 . When the same length of path is traversed by the same light in a medium other than vacuum, number of waves is 3 × 10 6 . When the same light travelling in vacuum, strikes the vacuum-medium interface at an angle of incidence 60 o , after refraction, the ray will deviate through an angle of

    What happens to the shining of diamond if it is dipped in a transparent oil?

    Two plane mirrors are inclined to each other at an angle θ . A ray of light is incident an one mirror and after two successive reflections, the final reflected ray becomes parallel to the incident ray. Then the value of θ is

    A bird is diving vertically downwards a fish in water with a velocity of 5 m/s. At the same time the fish is moving vertically downward away from the bird. If the distance of the fish as viewed by the bird remains unchanged, then velocity of the fish is μ = 4 / 3

    Critical angle of light passing from glass to air is minimum for

    An object of height h = 5 cm is located at a distance a = 12 cm from a concave mirror with focal length 10 cm. Then height of image:

    The intermediate image formed by a compound microscope has which of the following nature?

    A person can not see the objects beyond 50 cm. The power of a lens to correct this vision will be

    An object of height h= 5 cm is located at a distance a = 12 cm from a concave mirror with focal length 10 cm. Then height of image:

    Find the length of a telescope for which it is known that it has an objective lens of focal length 144 cm and an eye piece of focal length 6 cm.

    For a long sighted person, least distant of distinct vision is x meter. He wants to read news paper placed at x/2 meter from him. He uses spectacle having lenses of power x D. What is x :

    Which is the correct entity of Column 1 in Column 2. [Here, m is the magnification]: Column 1 Column 2 A m = − 2 a Convex mirror B m = − 1 2 b Concave mirror C m = +2 c Real image D m = + 1 2 d Virtual image

    In a compound microscope the objective lens and eye piece have focal length of 0.95 cm and 5 cm respectively, and are kept at a distance of 20 cm. The last image is formed at a distance of 25 cm from the eye piece calculate magnifying power:

    The resolution limit of eye is 1 min. At a distance a km from the eye two persons stand with a lateral separation of 3 m. For the two persons to be just resolved by the naked eye, should be :

    A plane mirror is approaching you with 10 cms − 1 you can see your image in it. At what speed will your image approach you?

    A point source of light S is placed on the axis of a lens of focal length 20 cm as shown. A screen is placed normal to the axis of lens at a distance x from it. Then INCORRECT statement.

    A student measures the focal length of a convex lens by putting an object pin at a distance ‘u’ from the lens and measuring the distance ‘v’ of the image pin. The graph between ‘u’ and ‘v’ plotted by the student look like

    Sun rays are focussed on a photo-sensitive plate with the help of convex lens. The photo-electric current is found to be i. If the lens is replaced by another similar lens of half the diameter and double the focal-length, the photo-current will now be

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