JEE Main2012PhysicsWave OpticsActual
In Young's double slit experiment, one of the slit is wider than other, so that the amplitude of the light from one slit is double of that from other slit. If I_m be the maximum intensity, the resultant intensity I when they interfere at phase difference is given by
Options
- AI_m 9 (4+5 )
- Bl _ m 3 (1+2 ^2 2 )
- CI_m 5 (1+4 ^2 2 )
- DI_m 9 (1+8 ^2 2 )
Correct answer
D. I_m 9 (1+8 ^2 2 )
Step-by-step solution
Let A₁=A₀, A₂=2 A₀ If amplitude of resultant wave is A then A ^2= A ₁^2+ A ₂^2+2 ~A ₁ A ₂ For maximum intensity, A _ ^2= A ₁^2+ A ₂^2+2 ~A ₁ A ₂ A^2 A_ ^2 = A₁^2+A₂^2+2 A₁ A₂ A₁^2+A₂^2+2 A₁ A₂ = A₀^2+4 A₀^2+2 (A₀ ) (2 A₀ ) A₀^2+4 A₀^2+2 (A₀ ) (2 A₀ ) I I _ m = 5+4 9 = 1+8 ^2( / 2) 9