Question

A short pulse of white light is incident from air to a glass slab at normal incidence. After travelling through the slab, the first colour to emerge is(a) blue(b) green(c) violet(d) red

Answer 1

the correct answer is option is (a).

Answer 2

Answer:

D) Red

Explanation:

The velocity of wave is expresses as v = fλ

When a light ray travels from one medium to another , the frequency remains same, thus v is proportional to λ or greater than the wavelength and the speed . All the transverse electromagnetic waves in vacuum have the same speed of ≈3⋅108m/s

All the colours of light travel with same velocity in air, but in glass their velocities are different. The velocity of red colour is the highest , hence after travelling through glass slab the red colour will emerge first