A parallel beam of monochromatic light of wavelength 450 nm passes through a long slit of width 0.2 mm. find the angular divergence in which most of the light is diffracted.

Options

A. `4.5xx10^(-3) " rad"`
B. `4.5 pi"rad"`
C. `2.25xx10^(-3) "rad"`
D. `9xx10^(-3) " rad"`

Answer

A

Explanation

Most of the light is diffracted between the two first order minima these minima occur at angles given by b `sin theta=pm lambda`
`rArrsin theta=pmlambda/b=pm(4.5xx10^(-7)m)/(0.2xx10^(-3)m)=pm2.25xx10^(-3)`
`rArrtheta~=2.25xx10^(-3)"rad"` (angle is very small)
The angular divergence `2theta=4.5xx10^(-3)"rad"`