A prism has a refracting angle of 60°. When placed in the position of minimum deviation, it produces a deviation of 30º. The angle of incidence is(a) 30°(b) 45°(c) 15°(d) 60°
Answers
Answer:
(b) 45° is the correct answer.
Explanation:
Refracting angle is the angle between two sides of prism through which the light is passed.
The angle of deviation is the angle between the incident ray and the emerging ray.
The angle of deviation is minimum when the angle of incidence so equal to angle of retraction.
The angle of incidence is defined as the angle between the incident ray and the normal to the incident surface.
Given data:
refracting angle of prism = 60°
It is placed in the position of minimum deviation, it produces a deviation.
Angle of deviation = 30º.
To Find:
The angle of incidence :?
We know that the least angle of deviation is given by the formula
= 2i-A
Here i= angle of incidence=?
Least angle of deviation= 30°
A= 60°
least angle of deviation= 2i-60
30=2i-60
90=2i
i=45°
Angle of incidence = 45°
Hence,
(b) 45° is the correct answer.