Question

Slit 5.0 cms wide is irradiated normally with microwaves of wavelength 1.0 cm. Then the angular spread of the central maximum on either side of the incident light is nearly

Answer 1

Here, the general equation for the points of zero intensity in the diffraction pattern of a single slit is -

a * sinT = n * λ

where, λ = wavelength of microwave  

            a  =  slit width

            n =  integer value 1,2,3....

For central maximum we will put n = 1 , to calculate the width of central maximum on either side of the incident light .

=> 5 * sinT = 1 * 1

But, for angle T very very small, sinT≈T .

Thus, 5 * T = 1 * 1

=> T = 1/5  radians

Thus, the angular spread of the central maximum on either side of the incident light is nearly 1/5  radians .