Deviation by Prism #8211; A prism is a homogeneous, transparent medium bounded by two plane surface inclined at an angle A with each other. If μ is the refractive index of the material of the prism, then [μ = sin i/sin r<sub>2</sub> = sin e/sin r<sub>2</sub>] The angle between the incident ray and the emergent ray is known as the angle of deviation (δ). For refraction through a prism, it is found that [i + e = A + δ]