A ray of light of intensity ' I ' is incident on a parallel glass slab at a point 'A' as shown in figure. It undergoes partial reflection and refraction. At each reflection 25 % of incident energy is reflected. The rays A B and A^1 B^1 undergo interference. The ratio I_ max / I_ min is

Step-by-step solution

Given an incident ray of intensity I₀ reflecting between two surfaces with reflection coefficient R = 1 4 and transmission coefficient T = 3 4 , the intensities of the two interfering rays are calculated. The first ray reflects directly from the upper surface with intensity I₁ = R I₀ = 1 4 I₀ . The second ray transmits through the upper surface, reflects from the lower surface, and transmits out again, with intensity I₂ = T R T I₀ = 3 4 1 4 3 4 I₀ = 9 64 I₀ . For interference between two waves, the intensity ratio