Question

• What happens to the width of the central diffraction pattern (in the single slit experiment) as the slit width is changed and why?

Answer 1

Initially when we decrease the slit width the intensity becomes low but after centain limit (when diffraction occurs) If we decrease the slit width the central diffraction maximum will be wider. And increase in slit width will cause the narrower central bright.

This will mainly happes due to limit of quantum mechanical Heisenberg Uncertainty principle. We know according to this principle ∆x ∆p > h/2π

NOw decrease in slit width will decrease ∆x to continue the limit of uncertainty principle ∆p of the passing photons will increase, and this will cause a wider central bright of diffraction.