CUET Physics MCQs Unit VI Optics

CUET Physics Ray Optics and Optical Instruments MCQs

Question : In image formation from spherical mirrors, only paraxial rays are considered because they
(a) are easy to handle geometrically
(b) contain most of the intensity of the incident light
(c) form nearly a point image of a point source
(d) show minimum dispersion effect

Answer: C

Question : The apparent flattening of the sun at sunset and sunrise is due to
(a) refraction
(b) diffraction
(c) total internal reflection
(d) interference

Answer: A

Question : The light reflected by a plane mirror may form a real image
(a) if the rays incident on the mirror are diverging
(b) if the rays incident on the mirror are converging
(c) if the object is placed very close to the mirror
(d) under no circumstances

Answer: B

Question : Which of the following is incorrect statement?
(a) the magnification produced by a convex mirror is always less than one
(b) a virtual, erect, same-sized image can be obtained using a plane mirror
(c) a virtual, erect, magnifield image can be formed using a concave mirror
(d) a real, inverted, same-sized image can be formed using a convex mirror.

Answer: D

Question : A point object is placed at the centre of a glass sphere of radius 6 cm and refractive index 1.5. The distance of the virtual image from the surface of the sphere is
(a) 2 cm
(b) 4 cm
(c) 6 cm
(d) 12 cm

Answer: C

Question : The field of view is maximum for
(a) plane mirror 
(b) concave mirror
(c) convex mirror 
(d) cylindrical mirror

Answer: C

Question : A person is six feet tall. How tall must a plane mirror be if he is able to see his entire length?
(a) 3 ft 
(b) 4.5 ft 
(c) 7.5 ft 
(d) 6 ft

Answer: A

Question : For reflection through spherical surfaces, the normal at the point of incidence is
(a) perpendicular to the principle axis and passes through the centre of curvature
(b) perpendicular to the focal plane and passes through the pole.
(c) perpendicular to the tangent plane at pole and passes through the focus.
(d) perpendicular to the tangent plane at the point of incidence and passes through the centre of curvature.

Answer: D

Question : When light is refracted into a medium,
(a) its wavelength and frequency both increase
(b) its wavelength increases but frequency remains unchanged
(c) its wavelength decreases but frequency remains unchanged
(d) its wavelength and frequency both decrease

Answer: B

Question : Total internal reflection can take place only if
(a) light goes from optically rarer medium (smaller refractive index) to optically denser medium
(b) light goes from optically denser medium to rarer medium
(c) the refractive indices of the two media are close to different
(d) the refractive indices of the two media are widely different

Answer: B

Question : Which of the following is not due to total internal reflection?
(a) Working of optical fibre
(b) Difference between apparent and real depth of pond
(c) Mirage on hot summer days
(d) Brilliance of diamond

Answer: B

Question : A parallel beam of light is incident on a converging lens parallel to its principal axis. As one moves away from the lens on the other side on its principal axis, the intensity of light
(a) remains constant
(b) continuously increases
(c) continuously decreases
(d) first increases then decreases

Answer: A

Question : A narrow beam of white light goes through a slab having parallel faces
(a) the light never splits in different colours
(b) the emergent beam is white
(c) the light inside the slab is split into different colours
(d) the light inside the slab is white

Answer: C

Question : If a glass prism is dipped in water, its dispersive power
(a) increases
(b) decreases
(c) does not change
(d) may increase or decrease depending on whether the angle of the prism is less than or greater than 60º

Answer: B

Question : By properly combining two prisms made of different materials, it is not possible to have
(a) dispersion without average deviation
(b) deviation without dispersion
(c) both dispersion and average deviation
(d) neither dispersion nor average deviation

Answer: D

Question : In primary rainbow what is the order of colours observed from earth ?
(a) Violet innermost, red outermost.
(b) Red innermost, violet outermost.
(c) Random.
(d) White and dark alternatively

Answer: A

Question : Astigmatism is corrected using
(a) cylindrical lens 
(b) plano-convex lens
(c) plano-concave lens 
(d) convex lens

Answer: A

Question: Two thin lenses are in contact and the focal length of the combination is 80 cm. If the focal length of one lens is 20 cm, then the power of the other lens will be
(a) 1.66 D
(b) 4.00 D
(c) – 100 D
(d) – 3.75 D

Answer: D

Question:   A bi-convex lens made of glass (refractive index 1.5) is put in a liquid of refractive index 1.7. Its focal length will
(a) decrease and change sign
(b) increase and change sign
(c) decrease and remain of the same sign
(d) increase and remain of the same sign

Answer: B

Question: If a glass prism is dipped in water, its dispersive power
(a) increases
(b) decreases
(c) does not change
(d) may increase or decrease depending on whether the

Answer: B

Question : Total internal reflection can take place only if
(a) light goes from optically rarer medium (smaller refractive index) to optically denser medium
(b) light goes from optically denser medium to rarer medium
(c) the refractive indices of the two media are close to different
(d) the refractive indices of the two media are widely different

Answer: B

Question : Electromagnetic radiation belonging to _________ region of spectrum is called light.
(a) 100 nm to 400 nm 
(b) 400 nm to 750 nm
(c) 750 nm to 10 nm 
(d) 1000 nm to 1400 nm

Answer: B

Question : An object is placed 40 cm from a concave mirror of focal length 20 cm. The image formed is
(a) real, inverted and same in size
(b) real, inverted and smaller
(c) virtual, erect and larger
(d) virtual, erect and smaller

Answer: A

Question : The equation n2/v - n1/v = n2 - n1/R holds true for
(a) only concave mirror
(b) only convex mirror
(c) both concave and convex mirror
(d) any type of reflecting surface

Answer: C

Question : If the light moving in a straight line bends by a small but fixed angle, it may be a case of
(a) reflection 
(b) refraction
(c) diffraction 
(d) both (a) & (b)

Answer: D

Question : Critical angle of light passing from glass to water is minimum for
(a) red colour 
(b) green colour
(c) yellow colour 
(d) violet colour

Answer: D

Question : The rays of different colours fail to converge at a point after going through a converging lens. This defect is called
(a) spherical aberration 
(b) distortion
(c) coma 
(d) chromatic aberration

Answer: D

Question : An astronomical telescope has a large aperture to
(a) reduce spherical aberration
(b) have high resolution
(c) increases span of observation
(d) have low dispersion

Answer: B

Question : When the incidence angle is equal to the angle of emergence of light from the prism the refracted ray inside the prism
(a) becomes parallel to the right face of prism
(b) becomes perpendicular to the base of prism
(c) becomes parallel to the base of prism
(d) becomes perpendicular to the left face of prism

Answer: C

Question : In secondary rainbow what is the order of colours observed from earth?
(a) Violet innermost, red outermost.
(b) Red innermost, violet outer most.
(c) Random.
(d) White and dark alternatively.

Answer: B

Question : The image formed by an objective of a compound microscope is
(a) real and diminished 
(b) real and enlarged
(c) virtual and enlarged 
(d) virtual and diminished

Answer: B

Question:  The rays of different colours fail to converge at a point after going through a converging lens. This defect is called
(a) spherical aberration
(b) distortion
(c) coma                       
(d) chromatic aberration

Answer: D

Question: The image formed by an objective of a compound microscope is
(a) real and diminished
(b) real and enlarged
(c) virtual and enlarged
(d) virtual and diminished

Answer: B

Question : A person is six feet tall. How tall must a plane mirror be if he is able to see his entire length?
(a) 3 ft
(b) 4.5 ft
(c) 7.5 ft
(d) 6 ft

Answer: A

Question : A virtual image larger than the object can be obtained by
(a) concave mirror 
(b) convex mirror
(c) plane mirror 
(d) concave lens

Answer: A

Question : Which of the following (referred to a spherical mirror) depends on whether the rays are paraxial or not?
(a) Pole 
(b) Focus
(c) Radius of curvature 
(d) Principal axis

Answer: B

Question : When the angle of incidence of a light ray is greater than the critical angle it gets
(a) critically refracted
(b) totally reflected
(c) total internally reflected
(d) totally refracted

Answer: C

Question : The speed of light in an isotropic medium depends on
(a) the nature of the source
(b) its wavelength
(c) its direction of propagation
(d) its intensity

Answer: B

Question :If D is the deviation of a normally falling light beam on a thin prism of angle A and δ is the dispersive power of the same prism then
(a) D is independent of A.
(b) D is independent of refractive Index.
(c) δ is independent of refractive index.
(d) δ is independent of A.

Answer: D

Question : The angle of prism is 60° and angle of deviation is 30°.In the position of minimum deviation, the values of angle of incidence and angle of emergence are:
(a) i = 45°; e = 50° 
(b) i = 30°; e = 45°
(c) i = 45°; e = 45° 
(d) i = 30°; e = 30°

Answer: C

Question : A normal eye is not able to see objects closer than 25 cm because
(a) the focal length of the eye is 25 cm
(b) the distance of the retina from the eye-lens is 25 cm
(c) the eye is not able to decrease the distance between the eye-lens and the retina beyond a limit
(d) the eye is not able to decrease the focal length beyond a limit

Answer: D

Question:  What causes chromatic aberration?
(a) Marginal rays
(b) Central rays
(c) Difference in radii of curvature of its surfaces
(d) Variation of focal length of lens with colour

Answer: D

Question : For reflection through spherical surfaces, the normal at the point of incidence is
(a) perpendicular to the principle axis and passes through the centre of curvature
(b) perpendicular to the focal plane and passes through the pole.
(c) perpendicular to the tangent plane at pole and passes through the focus.
(d) perpendicular to the tangent plane at the point of incidence and passes through the centre of curvature.

Answer: D

Question : Critical angle of light passing from glass to water is minimum for
(a) red colour     
(b) green colour
(c) yellow colour
(d) violet colour

Answer: D

Question : All of the following statements are correct except
(a) the magnification produced by a convex mirror is always less than one
(b) a virtual, erect, same-sized image can be obtained using a plane mirror
(c) a virtual, erect, magnifield image can be formed using a concave mirror
(d) a real, inverted, same-sized image can be formed using a convex mirror.

Answer: D

Question : The difference between reflection and total internal reflection is that
(a) the laws of reflection hold true for reflection but not for total internal reflection.
(b) total internal reflection can take place only when light travels from a rarer medium to a denser medium while reflection can take place vice-versa also.
(c) reflection can take place when light travels from a rarer medium to denser medium and vice-versa but total internal reflection can take place only when it travels from an optically denser to an optically rarer medium.
(d) reflection is a natural phenomena while total internal reflection is man-made.

Answer: C

Question : What causes chromatic aberration?
(a) Marginal rays
(b) Central rays
(c) Difference in radii of curvature of its surfaces
(d) Variation of focal length of lens with colour

Answer: D

Question : When white light enters a prism, it gets split into its constituent colours. This is due to
(a) high density of prism material
(b) because μ is different for different wavelength
(c) diffraction of light
(d) velocity changes for different frequency

Answer: B

Question : Identify the mismatch in the following
(a) Myopia - Concave lens
(b) For rear view - Concave mirror
(c) Hypermetropia - Convex lens
(d) Astigmatism - Cylindrical lens

Answer: B

Question:  The angular dispersion produced by a prism
(a) increases if the average refractive index increases
(b) increases if the average refractive index decreases
(c) remains constant whether the average refractive index increases or decreases
(d) has no relation with average refractive index.

Answer: A

Question : An object is placed 40 cm from a concave mirror of focal length 20 cm. The image formed is
(a) real, inverted and same in size
(b) real, inverted and smaller
(c) virtual, erect and larger
(d) virtual, erect and smaller

Answer: A

Question : A point source of light is placed in front of a plane mirror. Then 
(a) all the reflected rays meet at a point when produced backward
(b) only the reflected rays close to the normal meet at a point when produced backward.
(c) only the reflected rays making a small angle with the mirror, meet at a point when produced backward.
(d) light of different colours make different images.

Answer: A

Question : When light is refracted, which of the following does not change ?
(a) Wavelength 
(b) Frequency
(c) Velocity 
(d) Amplitude

Answer: B

Question : The focal length of a converging lens are fV and fR for violet and red light respectively. Then
(a) fV > fR
(b) fV = fR
(c) fV < fR
(d) any of the three is possible depending on the value of the average refractive index m

Answer: C

Question : The dispersive power of a prism depends on its
(a) shape
(b) size
(c) angle of prism
(d) refractive index of the monitorial of the prism

Answer: D

Question:  A convex lens is in contact with concave lens. The magnitude of the ratio of their powers is 2/3. Their equivalent focal length is 30 cm. What are their individual focal lengths (in cm)?
(a) –15, 10
(b) –10, 15
(c) 75, 50
(d) –75, 50

Answer: A

Question : In image formation from spherical mirrors, only paraxial rays are considered because they
(a) are easy to handle geometrically
(b) contain most of the intensity of the incident light
(c) form nearly a point image of a point source
(d) show minimum dispersion effect

Answer: C

Question : The turning back of light into the same medium after incident on a boundary separating two media is called
(a) reflection of light 
(b) refraction of light
(c) dispersion of light 
(d) interference of light

Answer: A

Question : Identify the wrong sign convention
(a) The magnification for virtual image formed by a convex lens is positive
(b) The magnification for real image formed by a convex lens is negative
(c) The height measured normal to the principal axis upwards is positive
(d) The magnification for virtual image formed by a concave lens is negative

Answer: D

Question : The angular dispersion produced by a prism
(a) increases if the average refractive index increases
(b) increases if the average refractive index decreases
(c) remains constant whether the average refractive index increases or decreases
(d) has no relation with average refractive index.

Answer: A

Question: A plano-convex lens is made of material of refractive index 1.6. The radius of curvature of the curved surface is 60 cm. The focal length of the lens is
(a) 50 cm
(b) 100 cm
(c) 200 cm
(d) 400 cm

Answer: B

Question : A glass slab of thickness 4 cm contains the same number of waves as 5 cm of water when both are traversed by the same monochromatic light. If the refractive index of water is 4/3, what is that of glass?
(a) 5/3
(b) 5/4
(c) 16/15
(d) 1.5

Answer: A

Question : Which of the following is correct for the beam which enters the medium?
(a) Travel as a cylindrical beam
(b) Diverge
(c) Converge
(d) Diverge near the axis and converge near the periphery

Answer: C

Question : Chromatic aberration in a lens is caused by
(a) reflection 
(b) interference
(c) diffraction
(d) dispersion

Answer: D

Question : The focal length of a normal eye-lens is about
(a) 1 mm 
(b) 2 cm
(c) 25 cm 
(d) 1 m

Answer: B

Question : When the angle of incidence of a light ray is greater than the critical angle it gets
(a) critically refracted         
(b) totally reflected
(c) total internally reflected
(d) totally refracted

Answer: C

Question : Which of the following phenomena is used in optical fibres ?
(a) Total internal reflection
(b) Scattering
(c) Diffraction
(d) Refraction

Answer: A

Question: A lens made of glass whose index of refraction is 1.60 has a focal length of + 20 cm in air. Its focal length in water, whose refractive index is 1.33, will be
(a) three times longer than in air
(b) two times longer than in air
(c) same as in air
(d) None of these

Answer: A

Question : The image formed by a concave mirror is
(a) always real
(b) always virtual
(c) certainly real if the object is virtual
(d) certainly virtual if the object is real

Answer: C

Question : Yellow light is refracted through a prism producing minimum deviation. If i1 and i2 denote the angle of incidence and emergence for this prism, then
\(a) i1 = i2
(b) i1 > i2
(c) i1 < i2 
(d) i1 + i2 = 90º

Answer: A

Question : A planoconvex lens of focal length 16 cm, is to be made of glass of refractive index 1.5. The radius of curvature of the curved surface should be
(a) 8 cm
(b) 12 cm
(c) 16 cm
(d) 24 cm

Answer: A

Question : Which light rays undergoes two internal reflection inside a raindrop, which of the rainbow is formed?
(a) Primary rainbow 
(b) Secondary rainbow
(c) Both (a) and (b) 
(d) Can’t say

Answer: B
 

CUET Physics Wave Optics MCQs

Question : If two sources are coherent, then the phase difference (Φ) between the waves produced by them at any point
(a) will change with time and we will have stable positions of maxima and minima.
(b) will not change with time and we have unstable positions of maxima and minima.
(c) Positions of will not change with time and we will have stable positions of maxima and minima.
(d) will change with time and we will have unstable positions of maxima and minima.

Answer: C

Question : In Young's double slit experiment, the locus of the point P lying in a plane with a constant path difference between the two interfering waves is
(a) a hyperbola 
(b) a straight line
(c) an ellipse 
(d) a parabola

Answer: A

Question : Transverse nature of light was confirmed by the phenomenon of
(a) refreaction of light
 (b) diffraction of light
(c) dispersion of light 
(d) polarization of light

Answer: D

Question : Wavefront is the locus of all points, where the particles of the medium vibrate with the same
(a) phase
(b) amplitude
(c) frequency
(d) period

Answer: A

Question : If Young’s double slit experiment is performed in water keeping the rest of the set-up same, the fringes will
(a) increase in width
(b) decrease in width
(c) remain unchanged
(d) not be formed

Answer: B

Question : Which of the following is correct for light diverging from a point source?
(a) The intensity decreases in proportion for the distance squared.
(b) The wavefront is parabolic.
(c) The intensity at the wavelingth does depend of the distance.
(d) None of these.

Answer: A

Question : A plane wave passes through a convex lens. The geometrical shape of the wavefront that emerges is
(a) plane
(b) diverging spherical
(c) converging spherical 
(d) None of these

Answer: D

Question : From Brewster’s law of polarisation, it follows that the anlge of polarisaiton depends upon
(a) the wavelength of light
(b) plane of polarisation’s orientation
(c) plane of vibration’s orientation
(d) None of these

Answer: A

Question : Coherence is a measure of
(a) capability of producing interference by wave
(b) waves being diffracted
(c) waves being reflected
(d) waves being refracted

Answer: A

Question : When unpolarised light is incident on a plane glass plate at Brewster’s angle, then which of the following statements is correct?
(a) Reflected and refracted rays are completely polarised with their planes of polarization parallel to each other
(b) Reflected and refracted rays are completely polarised with their planes of polarization perpendicular to each other
(c) Reflected light is plane polarised but transmitted light is partially polarised
(d) Reflected light is partially polarised but refracted light is plane polarised

Answer: C

Question : If Young’s double slit experiment is performed in water keeping the rest of the set-up same, the fringes will
(a) increase in width 
(b) decrease in width
(c) remain unchanged 
(d) not be formed

Answer: B

Question : The fringe width in a Young’s double slit experiment can be increased if we decrease
(a) width of slits
(b) separation of slits
(c) wavelength of light used
(d) distance between slits and screen

Answer: A

Question : If the width of the slit in single slit diffrection experiment is doubled, then the central maximum of diffraction pattern becomes
(a) broader and brighter 
(b) sharper and brighter
(c) sharper and fainter 
(d) broader adn fainter.

Answer: B

Question : What is the Brewester angle for air to glass transition?( μag = 1.5)
(a) tan (1.5) 
(b) sin (1.5)
(c) sin–1 (1.5) 
(d) tan–1 (1.5)

Answer: D

Question : Unpolarized light is incident on a plane glass surface The angle of incidence so that reflected and refracted rays are perpendicular to each other, them
(a) tan iβ= μ/2
(b) tan iβ= μ
(c) sin iβ= μ 
(d) cos iβ= μ

Answer: B

Question : Polaroid glass is used in sun glasses because
(a) it reduces the light intensity to half on account of polarisation
(b) it is fashionable
(c) it has good colour
(d) it is cheaper.

Answer: A

Question : The separation between successive fringes in a double slit arrangement is x. If the whole arrangement is dipped under water what will be the new fringe separation? [The wavelenght of light being used is 5000 Å]
(a) 1.5 x
(b) x
(c) 0.75 x
(d) 2 x

Answer: C

Question : The condition for observing Fraunhoffer diffraction from a single slit is that the light wavefront incident on the slit should be
(a) spherical
(b) cylindrical
(c) plane
(d) elliptical

Answer: C

Question : Huygen’s concept of secondary wave
(a) allows us to find the focal length of a thick lens
(b) is a geometrical method to find a wavefront
(c) is used to determine the velocity of light
(d) is used to explain polarisation

Answer: B

Question : In the Young’s Double slit experiment, when we place a converging lens after the slits and place the screen at the focus of the lens, it
(a) introduces an extra path difference in the parallel beam.
(b) introduces no path difference in the parallel beam.
(c) introduces an extra phase difference in the parallel beam.
(d) introduces an extra fringe in the diffraction pattern.

Answer: B

Question : Huygen’s concept of secondary wave
(a) allows us to find the focal length of a thick lens
(b) is a geometrical method to find a wavefront
(c) is used to determine the velocity of light
(d) is used to explain polarisation

Answer: B

Question : When a film is illuminated by white light, its upper portion appears dark. Path difference between two reflected beams at the spot must be
(a) zero
(b) λ/2
(c) 2 λ/2
(d) π

Answer: B

Question : Intensity of light depends on
(a) amplitude 
(b) frequency
(c) wavelength 
(d) velocity

Answer: A

Question : The fringe width for red colours as compared to that for violet colour is approximately
(a) 3 times 
(b) 2 times
(c) 4 times 
(d) 8 times

Answer: B

Question : A diffraction pattern is obtained by using beam of red. light what will happen, if red light is replced by the blue light?
(a) Bands disappear.
(b) Bands become broader and farther apart.
(c) No change will take place.
(d) Diffraction bands become narrow and crowded together.

Answer: D

Question : The diffraction effects in a microscopic specimen become important when the separation between two points is
(a) much greater than the wavelength of light used.
(b) much less than the wavelength of light used.
(c) comparable to the wavelength of light used.
(d) independent of the wavelength of light used.

Answer: C

Question : Light transmitted by nicol prism is
(a) unpolarised 
(b) plane polarised
(c) circularly polarised 
(d) elliptically polarised

Answer: B

Question : Light of wavelength 6.5 × 10–7 m is made incident on two slits 1 mm apart. The distance between third dark fringe and fifth bright fringe on a screen distant 1 m from the slits will be
(a) 0.325 mm
(b) 0.65 mm
(c) 1.625 mm
(d) 3.25 mm

Answer: C

Question : Optically active substances are those substances which
(a) produces polarised light
(b) produces double refraction
(c) rotate the plane of polarisation of polarised light
(d) converts a plane polarised light into circularly polarised light.

Answer: C

Question : Two coherent sources of intensity ratio 1 : 4 produce an interference pattern. The fringe visibility will be
(a) 1
(b) 0.8
(c) 0.4
(d) 0.6

Answer: B

Question : The locus of all particles in a medium, vibrating in the same phase is called
(a) wavelet
(b) fringe
(c) wave front
(d) None of these

Answer: C

Question : Spherical wavefronts, emanating from a point source,strike a plane reflecting surface. What will happen to these wave fronts, immediately after reflection?
(a) They will remain spherical with the same curvature,both in magnitude and sign.
(b) They will become plane wave fronts.
(c) They will remain spherical, with the same curvature, but sign of curvature reversed.
(d) They will remain spherical, but with different curvature, both in magnitude and sign.

Answer: C

Question : Two sources of light are said to be coherent, when they give light waves of same
(a) amplitude and phase
(b) wavelength and constant phase difference
(c) intensity and wavelength
(d) phase and speed

Answer: B

Question : In Young’s double slit experiment, one slit is covered with red filter and another slit is covered by green filter, then interference pattern will be
(a) red 
(b) green
(c) yellow 
(d) invisible

Answer: D

Question : When monochromatic light is replaced by white light in Fresnel’s biprism arrangement, the central fringe is
(a) coloured 
(b) white
(c) dark 
(d) None of these

Answer: B

Question : In the case of linearly polarized light, the magnitude of the electric field vector
(a) is parallel to the direction of propagation
(b) does not changes with time
(c) increases linearly with time
(d) varies periodically with time

Answer: D

Question : In Young’s double slit expt. the distance between two sources is 0.1 mm. The distance of the screen from the source is 20 cm. Wavelength of light used is 5460 Å. The angular position of the first dark fringe is
(a) 0.08°
(b) 0.16º
(c) 0.20º
(d) 0.32º

Answer: B

Question : When ordinary light is made incident on a quarter wave plate, the emergent light is
(a) linearly polarised
(b) circulary polarised
(c) unpolarised
(d) elliptically polarised

Answer: D

Question : The interfering fringes formed by a thin oil film on water are seen in yellow light of sodium lamp. We find the fringes
(a) coloured
(b) black and white
(c) yellow and black
(d) coloured without yellow

Answer: A

Question : Wavefront is the locus of all points, where the particles of the medium vibrate with the same
(a) phase 
(b) amplitude
(c) frequency
(d) period

Answer: A

Question : The device which produces highly coherent sources is 
(a) Fresnel biprism
(b) Young’s double-slit
(c) Laser
(d) Lloyd’s mirror

Answer: C

Question : The interfering fringes formed by a thin oil film on water are seen in yellow light of sodium lamp. We find the fringes
(a) coloured
(b) black and white
(c) yellow and black
(d) coloured without yellow

Answer: A

Question : Instead of using two slits, if we use two separate identical sodium lamps in Young’s experiment, which of the following will occur?
(a) General illumination
(b) Widely separate interference
(c) Very bright maxima
(d) Very dark minima

Answer: A

Question : When ordinary light is made incident on a quarter wave plate, the emergent light is
(a) linearly polarised 
(b) circulary polarised
(c) unpolarised 
(d) elliptically polarised

Answer: D

Question : In the propagation of electromagnetic waves, the angle between the direction of propagation and plane of polarisation is
(a) 0º 
(b) 45º
(c) 90º 
(d) 180º

Answer: A

Question : Light transmitted by nicol prism is
(a) unpolarised
(b) plane polarised
(c) circularly polarised
(d) elliptically polarised

Answer: B

Question : The fringe width in a Young’s double slit experiment can be increased if we decrease
(a) width of slits
(b) separation of slits
(c) wavelength of light used
(d) distance between slits and screen

Answer: B

Question : Two plane wavefronts of light, one incident on a thin convex lens and another on the refracting face of a thin prism. After refraction at them, the emerging wavefronts respectively become
(a) plane wavefront and plane wavefront
(b) plane wavefront and spherical wavefront
(c) spherical wavefront and plane wavefront
(d) spherical wavefront and spherical wavefront
(e) elliptical wavefront and spherical wavefront

Answer: C

Question : In Young’s Double slit experiment, if the distance between the slit and screen (D) is comparable with fringe width (B), the fringe pattern on screen will
(a) strictly be a parabola 
(b) strictly be a hyperbola
(c) be a elliptical 
(d) be a straight line

Answer: B

Question : The condition for observing Fraunhoffer diffraction from a single slit is that the light wavefront incident on the slit should be
(a) spherical 
(b) cylindrical
(c) plane 
(d) elliptical

Answer: C

Question : In the propagation of light waves, the angle between theplane of vibration and plane of polarisaiton is
(a) 0º 
(b) 90º 
(c) 45º 
(d) 80º

Answer: B

Question : In the propagation of light waves, the angle between the plane of vibration and plane of polarisaiton is
(a) 0º
(b) 90º
(c) 45º
(d) 80º

Answer: B

Question : The maximum number of possible interference maxima for slit-separation equal to twice the wavelength in Young’s double-slit experiment is
(a) three
(b) five
(c) infinite
(d) zero

Answer: B

Question : Which of the following, cannot produce two coherent sources?
(a) Lloyd’s mirror 
(b) Fresnel biprism
(c) Young’s double slit 
(d) Prism

Answer: D

Question : In Young’s double slit experiment, the minimum amplitude is obtained when the phase difference of super-imposing waves is (where n = 1, 2, 3, ...)
(a) zero 
(b) (2 n – 1) π
(c) n π 
(d) (n + 1) π

Answer: B

Question : Light waves can be polarised because they
(a) have high frequencies 
(b) have short wavelength
(c) are transverse 
(d) can be reflected

Answer: C

Question : The phenomena which is not explained by Huygen’s construction of wavefront
(a) reflection
(b) diffraction
(c) refraction 
(d) origin of spectr

Answer: D

Question : Laser light is considered to be coherent because it consists of
(a) many wavelengths
(b) uncoordinated wavelengths
(c) coordinated waves of exactly the same wavelength
(d) divergent beam

Answer: C

Question : The phenomenon of diffraction can be treated as interference phenomenon if the number of coherent sources is
(a) one 
(b) two
(c) zero 
(d) infinity

Answer: D

Question : If the width of the slit in single slit diffraction experiment is doubled, then the central maximum of diffraction pattern becomes
(a) broader and brighter
(b) sharper and brighter
(c) sharper and fainter
(d) broader adn fainter.

Answer: B

Question : When light suffers reflection at the interface between water and glass, the change of phase in the reflected wave is
(a) zero
(b) π
(c) π/2
(d) 2π

Answer: B

Question : Which of the following is not essential for two sources of light in Young’s double slit experiment to produce a sustained interference?
(a) Equal wavelength
(b) Equal intensity
(c) Constant phase relationship
(d) Equal frequency

Answer: B

Question : When monochromatic light is replaced by white light in Fresnel’s biprism arrangement, the central fringe is
(a) coloured
(b) white
(c) dark
(d) None of these

Answer: B

Question : The colour of bright fringe nearest to central achromatic fringe in the interference pattern with white light will be
(a) violet 
(b) red
(c) green 
(d) yellow

Answer: A

Question : Optically active substances are those substances which
(a) produces polarised light
(b) produces double refraction
(c) rotate the plane of polarisation of polarised light
(d) converts a plane polarised light into circularly polarised light.

Answer: C

Question : A plane wave passes through a convex lens. The geometrical shape of the wavefront that emerges is
(a) plane
(b) diverging spherical
(c) converging spherical
(d) None of these

Answer: C

Question : Distance between screen and source is decreased by 25%. Then the percentage change in fringe width is
(a) 20%
(b) 31%
(c) 75%
(d) 25%

Answer: D