JEE Main201912 Apr 2019Evening ShiftPhysicsWave OpticsActual
A system of three polarizers P 1 , P 2 , P 3 is set up such that the pass axis of P 3 is crossed with respect to that of P 1 . The pass axis of P 2 is inclined at 60 o to the pass axis of P 3 . When a beam of unpolarized light of intensity I o is incident on P 1 , the intensity of light transmitted by the three polarizers is I . The ratio I o / I equals (nearly):
Options
- A5.33
- B16.00
- C1.80
- D10.67
Correct answer
D. 10.67
Step-by-step solution
The intensity of light coming out of 1st Polaroid will be I 1 = I 0 2 From Malus law I = I 0 cos 2 ⁡ θ From Polaroid 2:     I = I 0 2 cos 2 ⁡ 30 ° = I 0 2 3 2 2 = 3 I 0 8 From Polaroid 3: I = 3 I 0 8 cos 2 ⁡ 60 ° = 3 I 0 8 1 2 2 = 3 I 0 32 Now, I 0 I = 32 3 = 10.67