Question

A ray of light travelling through rarer medium is incident at very small angle i on a glass slab and after refraction its velocity is reduced by 20%. The angle of deviation is ______.

Options

• `"i"/8`

• `"i"/5`

• `"i"/2`

• `(4"i")/5`

Answer 1

A ray of light travelling through rarer medium is incident at very small angle i on a glass slab and after refraction its velocity is reduced by 20%. The angle of deviation is `underlinebb("i"/5)`.

Explanation:

As given in the question, at glass-air interface velocity is reduced by 20% of the velocity of light.

So, deviation δ will be = 20% of i

= `(20xx"i")/100`

= `"i"/5`