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:

Step-by-step solution

The angle of minimum deviation is given as _ =i+e-A for minimum deviation aligned _ &=A then 2 A &=i+e aligned in case of _ i=e aligned 2 A &=2 i r₁=r₂= A 2 i &=A=90^ aligned from smell's law array l 1 i=n r₁ A=n A 2 2 A 2 A 2 =n A 2 2 A 2 =n array array l when A=90^ =i_ then n_ = 2 i=A=0 n_ =2 array