Question 1.
Which of-the following is not a property of light?
(a) It can travel through vacuum
(b) It has a finite speed
(c) It requires a material medium for its propagation
(d) It involve transportation energy

Answer

Answer: (c) It requires a material medium for its propagation

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Question 2.
Two points P and q are situated at the same distance from a source of light but on opposite sides. The plane difference between the light waves passing through P and q will be:
(a) n
(b) 2n
(c) \(\frac{π}{2}\)
(d) zero

Answer

Answer: (d) zero

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Question 3.
The phase difference between the electric and the magnetic field vectors in electromagnetic waves is
(a) \(\frac{π}{4}\)
(b) \(\frac{π}{2}\)
(c) π
(d) zero

Answer

Answer: (d) zero

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Question 4.
A ray of light travelling in air is incident of a glass slab. The ray gets partly reflected and partly refracted. The phase difference between the reflected and the refracted waves is :
(a) \(\frac{π}{2}\)
(b) \(\frac{π}{4}\)
(c) π
(d) zero

Answer

Answer: (c) π

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Question 5.
Which of the following cannot be polarised?
(a) radiowaves
(b) transverse waves
(c) sound waves
(d) X-rays

Answer

Answer: (c) sound waves

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Question 6.
Light year is the unit of:
(a) distance
(b) time
(c) intensity of light
(d) None of these

Answer

Answer: (a) distance

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Question 7.
If a mirror is approaching you at a speed of 10 ms^1, the speed with which your image approach you is:
(a) 10 ms^-1
(b) 5 ms^-1
(c) 20 ms^-1
(d) 15 ms^-1

Answer

Answer: (c) 20 ms^-1

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Question 8.
The refractive indices (R.I.) of glass and water with respect to air are 3/2 and 4/3 respectively. The R.I. of glass w.r. to w ater is:
(a) 8/9
(b) 9/8
(c) 7/6
(d) 2

Answer

Answer: (b) 9/8

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Question 9.
The angle of minimum deviation for an equilateral glass prism is 30°. Refractive index of the prism is:
(a) \(\frac{1}{√3}\)
(b) √2
(c) 1
(d) can’t be determined

Answer

Answer: (b) √2

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Question 10.
A beam of light is incident at 60° to a plane surface. The reflected and refracted rays are perpendicular to each other. What is the R.I. of the surface:
(a) \(\frac{1}{√3}\)
(b) √3
(c) \(\frac{1}{3}\)
(d) 3

Answer

Answer: (b) √3

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Question 11.
A concave mirror of focal length f produces an image n times the size of the object. If the image is real then the distance of the object is:
(a) (n – 1) f
(b) (n + 1) f
(c) (\(\frac{n+1}{n}\))f
(d) (\(\frac{n-1}{n}\))f

Answer

Answer: (c) (\(\frac{n+1}{n}\))f

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Question 12.
A convergent lens will become less convergent in :
(a) oil
(b) water
(c) both of (a) and (b)
(d) none of these

Answer

Answer: (b) water

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Question 13.
A thin glass (RI = \(\frac{3}{2}\)) lens has optical power of – 5D in air. Its optical power in a liquid medium with RI = 1.6 will be:
(a) -2.5 D
(b) 25 D
(c) -ID
(d) 0.625 D

Answer

Answer: (d) 0.625 D

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Question 14.
On reflection from a denser medium, a light wave suffers a phase difference of:
(a) π
(b) \(\frac{π}{2}\)
(c) \(\frac{π}{4}\)
(d) 2π

Answer

Answer: (a) π

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Question 15.
The branch of optics dealing with the formation of images using the concept of straight line propagation of light is called:
(a) geometrical optics
(b) physical optics
(c) corpuscular optics
(d) quantum optics

Answer

Answer: (d) quantum optics

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Question 16.
When light travels from one medium to another, which of the following does not change?
(a) frequency
(b) refractive index
(c) velocity
(d) wavelength

Answer

Answer: (a) frequency

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Question 17.
Two lens of power -15 D and +5 D are placed in contact co-axially. The focal length of equivalent lens is:
(a) -10 cm
(b) -20 cm
(c) +10 cm
(d) None

Answer

Answer: (a) -10 cm

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Question 18.
Refractive index of water and glass are \(\frac{4}{3}\) and \(\frac{5}{3}\). A light ray is going to water from glass. Then, its critical angle will be:
(a) sin^-1\(\frac{4}{5}\)
(b) sin^-1\(\frac{5}{6}\)
(c) sin^-1\(\frac{1}{2}\)
(d) sin^-1(\(\frac{2}{1}\))

Answer

Answer: (b) sin^-1\(\frac{5}{6}\)

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Question 19.
The air bubble inside water shine due to:
(a) Reflection
(b) Refraction
(c) T.l.R.
(d) None of these

Answer

Answer: (c) T.l.R.

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Question 20.
When a ray of light (white) enters a lens, undergoes a change is:
(a) wavelength
(b) velocity
(c) frequency
(d) both velocity and wavelength

Answer

Answer: (d) both velocity and wavelength

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Question 21.
Radio waves from an antenna travel with the velocity of:
(a) light
(b) sound
(c) ultrasonics
(d) supersonics

Answer

Answer: (a) light

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Question 22.
A point object is placed at the centre of a glass sphere of radius 6 cm 3 and RI = \(\frac{3}{2}\). The distance of virtual image from the surface of the sphere is :
(a) 2 cm
(b) 4 cm
(c) 6 cm
(d) 12 cm

Answer

Answer: (b) 4 cm

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Question 23.
The RI. of the material of a prism is √2 and its refracting angle is 30°. One of the refracting surface of the prism is made a mirror. A beam of monochromatic light entering the prism from the other face retraces its path, after reflection from mirror surface. The angle of incidence on prism is:
(a) 0°
(b) 30°
(c) 45°
(d) 60°

Answer

Answer: (c) 45°

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Question 24.
A telescope has an objective lens of 10 cm diameter and is situated at a distance of 1 km from two objects. The minimum distance between these two objects, which can be resolved by the telescope, when seen in the light of mean λ = 5000 A is of the order of:
(a) 5 mm
(b) 5 cm
(c) 0.5 m
(d) 5 m

Answer

Answer: (a) 5 mm

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Question 25.
When a beam of light is used to determine the position of an object, the maximum accuracy is achieved if the light is :
(a) polarized
(b) of longer λ
(c) of shorter λ
(d) of high intensity

Answer

Answer: (c) of shorter λ

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Question 26.
A convex lens is dipped in a liquid, whose R.I. is equal to that of R.I. of material of the lens. Then its focal length will:
(a) become zero
(b) become infinite
(c) reduce
(d) increase

Answer

Answer: (b) become infinite

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Question 27.
The velocity of light in vacuum is 3 × 10¹⁰ cms^-1. The velocity of light in a medium (µ = 1.5) is:
(a) 2 × 10¹⁰cms^-1
(b) 4.5 × 10¹⁰cms^-1
(c) 1.5 × 10¹⁰cms^-1
(d) None of these

Answer

Answer: (a) 2 × 10¹⁰cms^-1

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Question 28.
Which of the following is not essential for the formation of a pure spectrum?
(a) parallel beam of light
(b) narrow beam of light
(c) screen
(d) prism in the minimum deviation position

Answer

Answer: (c) screen

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Question 29.
A certain far-sighted person cannot see objects closer to the eye than 100 cm. The power of the lens which will enable him to read at a distance of 25 cm will be?
(a) 3D
(b) 1D
(c) 4D
(d) 2D

Answer

Answer: (a) 3D

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Question 30.
Which produces additional luminiscence in a fluorescent tube?
(a) infra red rays
(b) ultraviolet rays
(c) micro waves
(d) radio waves

Answer

Answer: (b) ultraviolet rays

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Question 31.
For achromatic combination of lenses, if we use two lenses of focal length f’ and f₁ dipersive power to ω and ω’ respectively, then
(a) ω = ω₀, ω’= 2ω₀, f’ = 2f
(b) ω = ω₀, ω’ = 2ω₀, f’ = -2f
(c) ω = ω₀, ω’ = 2ω₀, f’ = f/2
(d) ω = ω₀, ω’ = 2ω₀, f’ = -f/2

Answer

Answer: (d) ω = ω₀, ω’ = 2ω₀, f’ = -f/2

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Question 32.
ar point of a myopic eye is 40 cm. The dioptic power of a corrective lens is:
(a) 40 D
(b) -4 D
(c) -2.5 D
(d) -0.25 diopter

Answer

Answer: (c) -2.5 D

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Question 33.
Two thin lenses of focal lengths 20 cm and 25 cm are placed in contact. The effective power of the combination is:
(a) 45 D
(b) 9 D
(c) \(\frac{1}{9}\) D
(d) 6 D

Answer

Answer: (b) 9 D

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Question 34.
A blue cross on the white background is illuminated with white light and is observed through red filter. What is seen?
(a) A red cross on a black background
(b) A blue cross on a red background
(c) A red cross on a blue background
(d) A black cross on a red background

Answer

Answer: (d) A black cross on a red background

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Question 35.
The angle of deviation for a prism is greatest for:
(a) violet
(b) red
(c) orange
(d) yellow

Answer

Answer: (a) violet

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Question 36.
A double convex air bubble in water behaves as:
(a) Convergent lens
(b) divergent lens
(c) plane slab
(d) concave mirror

Answer

Answer: (b) divergent lens

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