Question

A single slit 1.2 mm wide is illuminated by 450-nm light produces a diffraction pattern. (a) What is the angular width of the central maximum (in degrees)? (b) What is the width of the central maximum (in cm) on a screen 6.0 m away?

Answer 1

a)

a = width of slit = 1.2 x 10^-3 m

$\lambda$ = wavelength = 450 x 10^-9 m

angualr width is given as

angular width = 2$\lambda$/a = 2 x 450 x 10^-9 / (1.2 x 10^-3 ) = 0.00075

b)

width of central maximum is given as

w = 2D$\lambda$/a

w = 2 x 450 x 10^-9 x 6 / (1.2 x 10^-3 ) = 0.0045 m = 0.45 cm