Question

5. For the angle of minimum deviation of a prism to
be equal to its refracting angle, the prism must be
made of a material whose refractive index
(1) Lies between 2 and 1
(2) Lies between 2 and 2
(3) Is less than 1
(4) Is greater than 2​

Answer 1

Answer:

Lies between 2 and √2

Explanation:

The angle of minimum deviation is given as

δ^min = i + e - A

for minimum deviation

δ^min = A then 2A = i + e in case of δ^mini = e

$2a = 2i \: \: r_{1} = r_{2} = \frac{a}{2} i$

= A = 90°

from smell’s law:

$1sini = nsinr$

$\sin \: a = nsin \frac{a}{2}$

$2 \sin \frac{a}{2} \cos \frac{ {a}{} }{2} = nsin \frac{a}{2}$

$2 \cos \frac{a}{2} = n$

When A = 90° = i

then n^min = √2

i = A0^n max = 2