The incident light on a Yound's experiment has wavelengths `400 nm` and `600 nm`. The distance between the two interfering sources is 2 mm and screen is at a distance of 1 m. The position from central fringe, where bright fringes of two wavelengths coincide first is at a distance of

Options

A. `0.6 mm`
B. `0.3 mm`
C. `6 mm`
D. `3 mm`

Answer

A

Explanation

`pxx400=qxx600 implies p/q=3/2`
`x_(min)=(pDlambda_(1))/d` or `(qDlambda_(2))/d`
`=(3xx1xx400xx10^(-9))/(2xx10^(-3))=6xx10^(-4)m=0.6 mm`