The slit width, when a light of wavelenght 6500Å is incident on a slit, if first minima for red light is at `30^(@)` is

Options

A. `1xx10^(-6) cm`
B. `5.2xx10^(-6) cm`
C. `1.3xx10^(-6) cm`
D. `2.6xx10^(-6) cm`

Answer

C

Explanation

`lamda=6500A^(@),n=1,a=?theta=30^(@)`
For `n^(th)` mininma, `sintheta=nlamda`
`:.a=(nlamda)/(sintheta)`
`=(1xx6.5xx10^(-7))/(sin30)`
`1.3xx10^(-6)m`