Question

In a single slit diffraction experiment, the width of the slit is made double the original width. How does this affect the size and intensity of the central diffraction band?

Answer 1

The width of the central diffraction band = $2D\times \frac{\lambda }{d}$

where d is the width of the slit.

So, on doubling the width of the slit, the size of the central diffraction band reduces to half value. But, the light amplitude becomes double, which increases the intensity of four fold.