A parallel beam of light of wave length 500 nm in incident normally on a single slit of width $10^{-6}m$. The light is focused by a convex lens on a screen placed in focal plane. What is the angle of diffraction for the first minimum formed?

30°

The correct answer is Option (2) → 30°

The condition for minima,

[m = order of minimum] $a\sin θ=mλ$

[a = width of the slit]

$[\theta \; =\; A$ngle of diffraction] 

$⇒10^{-6}\sin θ=1×500×10^{-9}$

$⇒\sin θ=0.5$

$⇒θ=\sin^{-1}\left(\frac{1}{2}\right)=30°$