Question

A ray of light falls on one face of an equilateral prism at an angle of45degree and emerges out at an angle of 43degree. Find the angle of deviation

Answer 1

Answer:

28 degree.

Explanation:

Since, the prism is equilateral hence all the angles of the prism will be same which is 60 degree and the side length will also be the same.

So, we get that the prism angle A is = 60 degree, the angle of incidence given in the question is i = 45 degree and the angle of emergence e is also given in the question as 43 degree.

The formulae of angle of deviation is given as:-

Angle of deviation = i + e – A

Hence, on substituting the values from the question we will get 45 + 43 – 60.

= 88 – 60

= 28 degree.

Answer 2

Given: A light ray falls on one of the faces of a prism at an angle 40o so that it suffers angle of minimum deviation of 30o.

To find the angle of prism and angle of refraction at the given surface

Solution:

According to the given criteria,

Angle of incidene, i=40∘

Angle of minimum deviation, δm=30∘

We know

δm=2i−A, where A is refracting angle of theprism

⟹A=2i−δm⟹A=2(40)−30⟹A=50∘

is the required angleof the prism.

And we also know in case of minimum deviation

A=2r, where r is refraction angle

So, r=2A=250⟹r=25∘

is the required angle of refraction.