In Young's double slit experiment, the intensity on the screen at a point where path difference is `lambda` is K. What will be the intensity at the point where path difference is `lambda//4`?

Options

A. (a) `K/4`
B. (b) `K/2`
C. (c) `K`
D. (d) Zero

Answer

B

Explanation

By using phase difference `varphi=(2pi)/(lambda)(Delta)`
For path difference `lambda`, phase difference `varphi_1=2pi` and for path difference `lambda//4`, phase difference `varphi_2=pi//2`.
Also by using `I=4I_0cos^2varphi/2impliesI_1/I_2=(cos^2(varphi_1//2))/(cos^2(varphi_2//2))`
`impliesK/I_2=(cos^2(2pi//2))/(cos^2(pi//2/2))=(1)/(1//2)impliesI_2=K/2`.