Question

A parallel beam of monochromatic light falls normally on a single slit of width \(a\) and a diffraction pattern is observed on a screen placed at distance \(D\) from the slit. Explain:
(I) the formation of maxima and minima in the diffraction pattern, and
(II) why the maxima go on becoming weaker and weaker with increasing order \(n\).

Hint:

For single-slit diffraction: \[ a\sin\theta=n\lambda \] gives the condition for minima. The central maximum is the brightest and has approximately twice the width of each secondary maximum.

Answer 1