MCQ
A beam with wavelength $\lambda$ falls on a stack of partially reflecting planes with separation d . The angle q that the beam should make with the planes so that the beams reflected from successive planes may interfere constructively is (where $n =1,2, \ldots \ldots$ )
- A$\sin ^{-1}\left(\frac{n \lambda}{d}\right)$
- B$\tan ^{-1}\left(\frac{ n \lambda}{ d }\right)$
- ✓$\sin ^{-1}\left(\frac{ n \lambda}{2 d}\right)$
- D$\cos ^{-1}\left(\frac{ n \lambda}{2 d}\right)$
