11)

If a man’s face is 25 cm in front of concave shaving mirror producing erect image 1.5 times the size of face, focal length of the mirror would be

Class 10 Physics

A)

75 cm

B)

25 cm

C)

15 cm

D)

35 cm

12)

As light travels from a rarer to a denser medium it will have

Class 10 Physics

A)

increased velocity

B)

decreased velocity

C)

decreased wavelength

D)

both (b) and (c)

13)

The angle of incidence i and refraction r are equal in a transparent slab when the value of i is

Class 10 Physics

A)

0°

B)

45°

C)

90°

D)

depend on the material of the slab

14)

The refractive index of transparent medium is greater than one because

Class 10 Physics

A)

Speed of light in vacuum < speed of light in tansparent medium

B)

Speed of light in vacuum > speed of light in tansparent medium

C)

Speed flight in vacuum = speed of light in tansparent medium

D)

Frequency of light wave changes when it moves from rarer to denser medium

15)

You are given three media A, B and C of refractive index 1.33, 1.65 and 1.46. The medium in which the light will travel fastest is

Class 10 Physics

A)

equal in all three media

B)

A

C)

B

D)

C

16)

Light from the Sun falling on a convex lens will converge at a point called

Class 10 Physics

A)

centre of curvature

B)

focus

C)

 radius of curvature

D)

 optical centre

17)

A divergent lens will produce

Class 10 Physics

A)

always real image

B)

always virtual image

C)

both real and virtual image

D)

none of these

18)

When object moves closer to convex lens, the image formed by it shift

Class 10 Physics

A)

away from the lens

B)

towards the lens

C)

 first towards and then away from the lens

D)

 first away and then towards the lens

19)

When object moves closer to a concave lens the image by it shift

Class 10 Physics

A)

away from the lens on the same side of object

B)

toward the lens

C)

away from the lens on the other side of lens

D)

first towards and then away from the lens

20)

A magnified real image is formed by a convex lens when the object is at

Class 10 Physics

A)

F

B)

between F and 2F

C)

2F

D)

(a) and (b) both