MHT CET202521 Apr 2025Morning ShiftPhysicsWave OpticsActual
Three polarised sheets are co-axially placed. Pass axis of polaroids 2 and 3 make 30^ and 90^ with pass axis of polaroid sheet. If I ₀ is the intensity of unpolarised light entering sheet 1 , the intensity of the emergent light through sheet 3 is ( 30^ = 3 / 2, 90^ =0, 60^ =1 / 2 )
Options
- Azero
- B3 I ₀ 32
- C3 I ₀ 8
- D3 I ₀ 16
Correct answer
B. 3 I ₀ 32
Step-by-step solution
Intensity through three polarizers: unpolarized incident light of intensity I₀ becomes I₀ 2 after the first polarizer due to averaging. Light then polarized at 30^ relative to the second polarizer's axis transmits with intensity I₂ = I₀ 2 ^2(30^ ) = 3I₀ 8 . The third polarizer is at 90^ to the first, hence 60^ to the second's axis, giving I₃ = I₂ ^2(60^ ) = 3I₀ 8 1 4 = 3I₀ 32 . 3I₀ 32