Question

A parallel beam of monochromatic light of wavelength 5 × 10^-7 m is incident normally on a single narrow slit of width 10^-3 mm. At what angle of diffraction, the first minima are observed? 

Options

• sin^-1 (1) 

• `sin^-1 (1/2)`

• `sin^-1 (sqrt3/2)`

• `sin6-1(1/sqrt2)`

Answer 1

`underline(sin^-1 (1/2))`

Explanation:

`sin theta = lambda/a = (5 xx 10^-7 m)/(10^-6 m) = 0.5 = 1/2`

∴ `theta = sin^-1(1/2)`