In Young's double slit experiment, the intensity of light at a point on the screen where the path difference is `lambda=l`. The intensity of light at a point where the path difference becomes `lambda//3` is

Options

A. (a) `l/4`
B. (b) `l/3`
C. (c) `l/2`
D. (d) `l`

Answer

A

Explanation

`Iprop4a^2co s^2phi/2`
In the first case, `phi=2pi`
`:. I^'prop4a^2`
In the second case, `phi=(2pi)/(3)`
`:. I^'prop4a^2co s^2(2pi)/(3)` or `I^'propa^2`
`I^'/I=1/4` or `I^'=I/4`