A parallel beam of wavelength `lambda=450xx10^9m` passes through a long slit of width `2xx10^-4m`. The angular divergence for which most of light is diffracted is

Options

A. (a) `5.4xx10^-4rad`
B. (b) `4.5xx10^-3rad`
C. (c) `3.5xx10^-3rad`
D. (d) `2.8xx10^-4rad`

Answer

B

Explanation

Most of the light is diffracted between the two first order minima.
`:.` Required angle=`2theta`
`=2sin theta=(2lambda)/(d)=(2xx450xx10^-9)/(2xx10^-4)`
`=450xx10^-5radian=4.5xx10^-3radian`