NTA Abhyas JEE Main2020PhysicsWave OpticsPractice
A ray of light of intensity I is incident on a parallel glass-slab at the point A and it undergoes partial reflection and refraction as shown in the figure. At each reflection, 25 %   of the incident energy is reflected and the rest is transmitted. If the rays A B and A ′ B ′   undergo interference, then the ratio I max I min is
Options
- A4 : 1
- B8 : 1
- C7 : 1
- D49 : 1
Correct answer
D. 49 : 1
Step-by-step solution
From figure I 1 = I 4 and I 2 = 9 I 64 ⇒ I 2 I 1 = 9 16 By using I m a x I m i n = I 2 I 1 + 1 I 2 I 1 - 1 2 = 9 1 6 + 1 9 1 6 - 1 2 = 4 9 1