Ray Optics Test

Result

Ray Optics Test - 31

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Weekly Quiz Competition

Question 1
4 / -1

A point source of light B, placed at a distance L in front of the centre of a mirror of width d, hangs vertically on a wall. A man walks in front of the mirror along a line parallels to the mirror at a distance 2 L from it as shown in Fig. The greatest distance over which he can see the image of the light source in the mirror is

A
d/2

B
d

C
2d

D
3d

Solution
Question 2
4 / -1

Magnifying power of telescope can be increased by

A
increasing the length of telescope

B
increasing focal length of objective

C
increasing the diameter of objective

D
increasing the focal length of eye piece

Solution
Question 3
4 / -1

A doctor advises a patient to use spectacles with a convex lens of focal length 40 cm in contact with a concave lens of focal length 25 cm. What is the power of the combination?

A
– 6.5 D

B
– 1.5 D

C
6.5 D

D
1.5 D

Solution
Question 4
4 / -1

A disc is placed on a surface of pond which has refractive index 5/3. A source of light is placed 4 m below the surface of liquid. The minimum radius of disc needed so that light is not coming out is

A
∞

B
3 m

C
6 m

D
4 m

Solution
Question 5
4 / -1

Wave lengths of light used in an optical instrument are λ = 4000 Ǻ and λ = 5000 Ǻ. The ratio of their respective resolving power is

A
16 : 25

B
5 : 4

C
4 : 5

D
9 : 1

Solution
Question 6
4 / -1

The objective of an astronomical telescope has a large aperture to

A
reduce spherical aberration

B
increase span of observations

C
have high resolution

D
have low dispersion

Solution
Question 7
4 / -1

The Cauchy’s dispersion formula is

A

B

C

D

Solution
Question 8
4 / -1

An observer can see through a pin hole, the top end of a thin rod of height h placed as shown in Fig. The beaker height is 3h and its radius is h. When the beaker is filled with a liquid upto a height 2h, he can see the lower end of the rod. Then the refractive index of the liquid is

A
5/2

B

C
3/2

D

Solution
Question 9
4 / -1

The image formed by an objective of a compound microscope is

A
virtual and diminished

B
real and diminished

C
real and enlarged

D
virtual and enlarged
Question 10
4 / -1

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
become zero

B
become infinite

C
reduce

D
increase

Solution