In Young.s double slit experiment, using monochromatic light of wavelength `lamda `, the intensity of light at a point on the screen where path difference is `lamda ` is K units. The intensity of light at a point where path difference is `lamda//3` is.

Options

A. 4K
B. K
C. 2K
D. `K//4`

Answer

D

Explanation

`I= 4I_theta cos^2 phi `
` phi = ( 2 pi)/( lamda) D = (2 pi)/(3 )`
` I= 4I_0 1/4 = I_0 …… (1) `
` "//"^(ly) I=K= 4I_0 …..(2)`
From eqns 1 and 2 we arrive at option (D )