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

Options

A. `(I)/(4)`
B. `(I)/(3)`
C. `(I)/(2)`
D. `I`

Answer

a

Explanation

`I prop 4a^(2) cos^(2) (phi)/(2)`
In the first case, `phi = 2 pi`
`:. I' prop 4a^(2)`
In the second case, `phi = (2 pi)/(3)`
`:. I' prop 4a^(2) cos^(2) ((2 pi)/(3))` or `I' prop a^(2)`
`(I')/(I) = (1)/(4)` or ` I' = (I)/(4)`