Angular width of a central max. is 30° when the slit is illuminated by light of wavelength 6000 Å. Then width of the slit will be approx.

$12 × 10^{–6} m$ $12 × 10^{–7} m$ $12 × 10^{–8} m$ $12 × 10^{–9} m$

$12 × 10^{–7} m$

Angular width = 2θ = 30° $∴\sin 30° =\frac{λ}{a}$ $∴a=\frac{λ}{\sin 30°} =\frac{6000×10^{-10}}{1/2}=12000×10^{-10} m$ $=12 × 10^{–7} m$