PHYS102: Introduction to Electromagnetism

When you see drawings of light rays, do not confuse them with pictures of electric or magnetic field lines. We will not be talking about these fields at all in the context of geometric optics. Light rays always indicate the direction in which the corresponding electromagnetic wave is traveling, and that direction happens to be precisely perpendicular to the orientation of the magnetic and electric field lines at any given point!

Watch this video, which covers the material in this section and introduces the next three sections of our textbook which we will discuss next.