Answer to Question #161550 in Electricity and Magnetism for James Woatsi

Question

Explain the behavior of a diffracted wave on

a) a slit

b) the aperture

Answer 1

a) Light passing through a single slit forms a diffraction pattern somewhat different from those formed by double slits or diffraction gratings. Note that the central maximum is larger than maxima on either side and that the intensity decreases rapidly on either side. In contrast, a diffraction grating produces evenly spaced lines that dim slowly on either side of the center.

b) Diffraction also limits the detail shows three different circumstances of resolution limits due to diffraction:

(a) shows a light passing through a small circular aperture. You do not see a sharp circular outline, but a spot with fuzzy edges. This is due to diffraction similar to that through a single slit.

(b) shows two point sources close together, producing overlapping images. Due to the diffraction, you can just barely distinguish between the two point sources.

(c) shows two point sources which are so close together that you can no longer distinguish between them.

This effect can be seen with light passing through small apertures or larger apertures. This same effect happens when light passes through our pupils, and this is why the human eye has limited acuity.