A slit 5 cm wide when irradiated by waves of wavelength 10 mm results in the angular spread of the central maxima on either side of incident light by about

1/2 radian 1/4 radian 3 radian 1/5 radian

1/5 radian

Angular spread on either side is given by $θ=\frac{λ}{a}=\frac{1}{5}$ radians