OPTICS

1 )

The velocity of light is maximum in a medium of _______ .

diamond

water

glass

vacuum

View Solution

Answer :

The velocity of light is maximum in vacuum.

2 )

A light of wavelength 320 nm enters in a medium of refractive index 1.6 from the air of refractive index 1.0. The new wavelength of light in the medium will be ______ nm.

520

400

320

200

View Solution

Answer :

∴ wavelength in the new medium = λ’

and if λ is wavelength in air then λ’ = (λ/n)

∴ λ’ = {(320nm) / 1.6} = 200 nm

3 )

"Bhautik" runs towards a plane mirror with a speed of 20 ms^–1 , what is the speed of his image ?

45 ms^â€“1

20 ms^â€“1

15 ms^â€“1

7.5 ms^â€“1

View Solution

Answer :

Speed of object = speed of image = 20 m/s

4 )

A ray of light is incident at an angle 30° on a mirror, The angle between normal and reflected ray is ________ .

15Â°

30Â°

45Â°

60Â°

View Solution

Answer :

ray is making 30° with the mirror. hence angle of incidence = 90 – 30 = 60°

angle of incidence = angle of reflection = 60°.

5 )

The no. of images formed between two parallel plane mirror are ________ .

âˆž

180

360

View Solution

Answer :

number of image formed = n = (360 / θ) – 1 or n = (360 / θ)

as mirrors are parallel, θ = 0°, hence n = ∞.

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