Question

Light of wavelength 587.5 nm illuminates a slit, of width 0.74 mm.

(a) At what distance from the slit should a screen be placed if the first minimum in the diffraction pattern is to be 0.82mm from the central maximum?
________m
(b) Calculate the width of the central maximum.
_________ mm

Answer 1

Wavelength  ?= 587.5 * 10 ^ -9 m

Slit width d = 0.74 * 10 ^ -3 m

Distance of the 1 st minimum from the central maximum y =0.82 * 10 ^ -3 m

We know condition for 1 st minimum   dsin ?= ?

For small angles d ( y/D ) = ?

From this distance of the screen from slit D = y d/ ?

plug the values weget D = 1.0328 m

(b). width of central maximum = 2y = 1.64* 10 ^ -3m

                                               = 1.64 mm