A ray of light suffers a minimum deviation when incident on an equilateral prism of refractive index ( 2 ). The angle of incidence is

Step-by-step solution

Angle of deviation =i₁+i₂-A where A is angle of prism A=r₁+r₂ =i₁+i₂- (r₁+r₂ ) At minimum deviation r₁=r₂ and i₁=i₂ =2 i₁-2 r₁ and A=2 r₁ For equilateral prism, A =60^ 2 r₁=60^ r₁=30^ Now we know i₁= r₁ i₁= ⁻¹ ( r₁ )i₁= ⁻¹ ( 2 30^ )= ⁻¹ ( 2 1 2 )= ⁻¹ ( 1 2 ) i₁=45^