Light is incident at an angle `phi` with the normal to a plane containing two slits of separation d. Select the expression that correctly describes the positions of the interference maxima in terms of the incoming angle `phi` and outgoing angle `theta`.

Options

A. `sin phi = sin theta = (m + (1)/(2)) (lambda)/(d)`
B. `d sin theta = m lambda`
C. `sin phi - sin theta = (m + 1) (lambda)/(d)`
D. `sin phi + sin theta = m (lambda)/(d)`

Answer

d

Explanation

Path difference `= d sin phi + d sin theta`
For maxima, `Delta x = m lambda`
`implies sin phi + sin theta = (m lambda)/(d)`