Question:
In deriving the single slit diffraction pattern, it was stated that the intensity is zero at angles of nλ/a. Justify this by suitably dividing the slit to bring out the cancellation.
Solution:
Let “a” be the width of a single slit. The single slit is further divided into n smaller slits of width a’.
a’ = a/n
Each of the smaller slits should produce zero intensity for the single slit to produce zero intensity.
For this to happen, the angle of diffraction, θ = λ/a’
⇒ θ = λ/(a/n)
or, θ = nλ/a
Therefore, in deriving the single slit diffraction pattern, it was stated that the intensity is zero at angles of nλ/a.