A fraunhofer diffraction pattern is formed by a light,of wavelength 600nm, through a slit if width 1.2 `mu`m . Find the angular position of the first minimum and angular width of the central maximum.

Explanation

If angular position of first minimum with respect to central maximum be `theta`, then
`sin theta = (lambda)/(a) = (600xx 10^(-9))/(1.2 xx 10^(-6)) = 0.5 = (1)/(2) = sin 30^(@)`
`therefore " " theta = 30^(@) `[ here,`lambda = 600 "nm" = 600 xx 10^(-9) `m,
a = 1.2`mu m = 1.2 xx 10^(-6)`m]
`therefore ` Angular width of central maximum = 2`theta = 2 xx 30^(@) = 60^(@)`