Let `S_(1)` and `S_(2)` be the two slits in Young's double-slit experiment. If central maxima is observed at P and angle `/_ S_(1) P S_(2) = theta`, then fringe width for the light of wavelength `lambda` will be (assume `theta` to be a small angle)

Options

A. `lamda//theta`
B. `lamdatheta`
C. `2lamda//theta`
D. `lamda//2theta`

Answer

A

Explanation

As distance between `S_(1)` & `S_(2)` is very much medium. And equal to 'd' so the angle made at 'P' is very much small
`therefore` angle `=(Arc)/(D)impliestheta=(d)/(D)`
`therefore` fringe width `=(lamdaD)/(d)=(lamda)/(theta)(because(d)/(D)=theta)`