Question

In Young’s double–slit experiment, the intensity of light at a point on the screen where the path difference is Kλ is K (λ being the wavelength). The intensity at a point where the path difference is λ/4 will be:

• A. \(K\)
• B. \(K/4\)
• C. \(K/2\)
• D. Zero

Hint:

Always convert path difference to phase difference first.

Answer 1

The Correct Option is B

Step 1: Intensity in interference: I ∝ cos²((φ)/(2))
Step 2: For path difference λ/4: φ = (2π)/(λ)·(λ)/(4) = (π)/(2)
Step 3: I = Imaxcos²((π)/(4)) = fracImax2 ⟹ I = (K)/(4)