For the angle of minimum deviation of a prism to be equal

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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

Correct Option: B

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_min = i = e
2A = 2i r₁ = r₂ = A/2
i = A = 90°
from smell’s law
1 sin i = n sin r₁
sin A = n sin A/2

2 sin	A	cos	A	n sin	A	cos
	2		2		2

2 cos	A	= n
	2

when A = 90° = i_{min/sub>
then n_{min/sub> = √2
i = A = 0 n_{min/sub> = 2}}}