CBSE Class 12 Physics Ray Optics And Wave Optics Worksheet

Question. A plane convex 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. Critical angle of light passing from glass to water is minimum faor
(a) red colour
(b) green colour
(c) yellow colour
(d) violet colour

Answer: D

Question. An object is placed at a distance 2f from the pole of a convex mirror of focal length f. The linear magnification is
(a) 1/3
(b) 2/3
(c) 3/4
(d) 1

Answer: A

Question. A vessel is half filled with a liquid of refractive index μ. The other half of the vessel is filled with an immiscible liquid of refrative index 1.5 μ. The apparent depth of the vessel is 50% of the actual depth. Then μ is
(a) 1.4
(b) 1.5
(c) 1.6
(d) 1.67

Answer: D

Question. An electromagnetic radiation of frequency n, wavelength λ, travelling with velocity v in air enters in a glass slab of refractive index (μ). The frequency, wavelength and velocity of light in the glass slab will be respectively
(a) n , λ/μ and v/μ 
(b) n , 2λ and v/μ 
(c) n/μ , λ/μ and v/μ
(d) 2π/μ , λ/μ and v

Answer: A

Question. The wavelength of a monochromatic light in vacuum is λ. It travels from vacuum to a medium of absolute refractive index μ. The ratio of wavelength of the incident and refracted wave is
(a) μ² : 1
(b) 1 : 1
(c) μ : 1
(d) 1 : μ

Answer: C

Question. A man 160 cm high stands in front of a plane mirror. His eyes are at a height of 150 cm from the floor. Then the minimum length of the plane mirror for him to see his full length image is
(a) 85 cm
(b) 170 cm
(c) 80 cm
(d) 340 cm

Answer: C

Question. It is desired to photograph the image of an object placed at a distance of 3 m from plane mirror. The camera, which is at a distance of 4.5 m from mirror should be focussed for a distance of
(a) 3 m
(b) 4.5 m
(c) 6 m
(d) 7.5 m

Answer: D

Question. The focal lengths of objective and eye lens of an astronomical telelscope are respectively 2 meter and 5 cm. Final image is formed at
(i) least distance of distinct vision
(ii) infinity Magnifying power in two cases will be
(a) – 48, – 40
(b) – 40, – 48
(c) – 40, + 48
(d) – 48, + 40

Answer: A

Question. The layered lens as shown is made of two types of transparent materials-one indicated by horizontal lines and the other by vertical lines. The number of images formed of an object will be 

(a) 1
(b) 2
(c) 3
(d) 6

Answer: B

Question. A thin convergent glass lens (μ_g = 1.5) has a power of + 5.0 D. When this lens is immersed in a liquid of refractive index m, it acts as a divergent lens of focal length 100 cm. The value of μ must be
(a) 4/3
(b) 5/3
(c) 5/4
(d) 6/5

Answer: B

Question. In an astronomical telescope in normal adjustment a straight black line of lenght 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 l. The magnification of the telescope is :
(a) L/I - 1
(b) L+1/L-1
(c) L/I
(d) L/I + 1

Answer: C

Question. A diver inside water sees the setting sun at
(a) 41° to the horizon
(b) 49° to the horizon
(c) 0° to the horizon
(d) 45° to the horizon

Answer: A

Question. A ray of light travelling in a transparent medium of refractive index μ , falls on a surface separating the medium from air at an angle of incidence of 45°. For which of the following value of m the ray can undergo total internal reflection?
(a) μ = 1.33
(b) μ = 1.40
(c) μ = 1.50
(d) μ = 1.25

Answer: C

Question. Two convex lenses of focal lengths f₁ and f₂ are mounted coaxially separated by a distance. If the power of the combination is zero, the distance between the lenses is
(a) | f₁ - f₂ |
(b) f₁ + f₂
(c) f₁ f₂/| f₁ - f₂ |
(d) f₁ f₂/f₁ + f₂

Answer: B

Question. A ray incident at 15° on one refracting surface of a prism of angle 60° suffers a deviation of 55°. What is the angle of emergence ?
(a) 95°
(b) 45°
(c) 30°
(d) None of these

Answer: D

Question. A thin prism of angle 15º made of glass of refractive index μ₁ = 1.5 is combined with another prism of glass of refractive index μ₂ = 1.75. The combination of the prism produces dispersion without deviation. The angle of the second prism should be
(a) 7°
(b) 10°
(c) 12°
(d) 5°

Answer: B

Question. A combination is made of two lenses of focal length f and f' in contact, the dispersive powers of the materials of the lenses are w and w'. The combination is achromatic, when
(a) ω = ω₀, ω' = 2ω₀ f' = 2f
(b) ω = ω₀, ω' = 2ω₀ f' = f/2
(c) ω = ω₀, ω' = 2ω₀ f' = –f/2
(d) ω = ω₀, ω' = 2ω₀ f' = –2f

Answer: D

Question. If two mirrors are kept at 60º to each other, then the number of images formed by them is
(a) 5
(b) 6
(c) 7
(d) 8

Answer: A

Question. We wish to see inside an atom. Assume the atom to have a diameter of 100 pm. This means that one must be able to resolve a width of say 10 pm. If an electron microscope is used the energy required should be
(a) 1.5 keV
(b) 50 keV
(c) 150 keV
(d) 1.5 MeV

Answer: B

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