PHYS102: Introduction to Electromagnetism

Watch this video, which introduces us to the most important effects that all waves can produce. The discussion talks specifically about light even though the explanations apply to all waves. The reason why light is our main example here has to do with the ambiguous nature of light which was mentioned when we introduced the concept of the photon: light is different from water waves because it does not require a medium to propagate. This makes it much harder to prove that light is actually a wave, because we cannot directly observe the ripples that make a light wave, as we see the ripples on a pond when a water wave passes through.

What we have to do to prove that light is a wave is: verify that light shows all the same effects that only waves (not particles) can produce. Geometric optics cannot help us here, because the rays we have been talking about could still in principle be interpreted as the trajectories of the little particles we called photons.

The main thing waves can do and particles (in the classical sense) cannot is for two of them to occupy the same region of space. When this happens with waves, we get the effect called interference. Building on this, we can observe the additional effects discussed in this video.