Question

A light ray is incident on a smooth surface at an angle of incidence 20° find the angle of deviation

Answer 1

Answer:

70°

Step-by-step explanation:

angle of deviation=90-angle of incidence

=90-20=70°

Answer 2

Step-by-step explanation:

Given:

The angle of incidence $(i)$ $=20$°

To find:

The angle of deviation (δ).

Solution:

• Deviation angle is defined as the angle obtained from the difference between the angle of incidence and the angle of refraction created by the rays of light traveling from one medium to another with a different refractive index.

• The angle of deviation (δ)$=i-r$

Where $i$ is the angle of incidence, $r$ is the angle of refraction.

But in the given question only has the angle of incidence $(i)$.

⇒ Since the angle of incident $(i)$ = The angle of refraction $(r)$

Hence $r=20$° and here the angle of deviation can be calculated as follows,

⇒ δ $=$ $180$° $-(i+r)$

       $=$ $180$°$-($ $20$° $+$ $20$°$)$

∴ The angle of deviation δ $=140$°.

Answer:

Hence the angle of deviation is δ$=140$°.