In a single slit diffraction method, the distance between slit and screen is `1m`. The size of the slit is `0.7mm` and second maximum is formed at the distance of `2mm` from the centre of the screen, then find out the wavelength of light.

Options

A. (a) `4800Å`
B. (b) `3600Å`
C. (c) `5600Å`
D. (d) `2500Å`

Answer

C

Explanation

Path difference, `asintheta=(5lambda)/(2)`
`atantheta=(5lambda)/(2)` (as `theta` is small)
`a*y/D=(5lambda)/(2)`
`lambda=(2ay)/(5D)=(2xx0.7xx10^-3xx2xx10^-3)/(5xx1)=(2.8)/(5)xx10^-6` meter
`=28/5xx10^-7=5600Å`