In the Young's double slit experiment, if the phase difference between the two waves interfering at a point is `phi`, the intensity at that point can be expressed by the expression

Options

A. (a) `I=sqrt(A^2+B^2cos^2varphi)`
B. (b) `I=A/Bcosvarphi`
C. (c)`I=A+Bco svarphi/2`
D. (d) `I=A+Bcosvarphi`

Answer

D

Explanation

`I=a_1^2+a_2^2+2a_1a_2cosvarphi`
Put `a_1^2+a_2^2=A` and `a_1a_2=B :. I=A+B cos varphi`