Chad provides an introduction to Electromagnetic Waves. The lesson begins with a description of Maxwell's Equations which combined electricity and magnetism into a unified theory of electromagnetism. His theory ultimately lead him to predict the existence of what we now call electromagnetic waves which have perpendicular electric and magnetic fields and propagate at the speed of light!

A major novelty of Maxwell's ideas was that a changing electric field would cause a magnetic field just as a changing magnetic field causes an electric field, and he was right. And in line with his conclusions is the fact that alternating current produces electromagnetic waves. And these electromagnetic waves have all the properties of other waves we are familiar with; they have a wavelength, frequency, and speed and display interference patterns similar to those we observe with other waves. Specifically, electromagnetic waves are transverse waves. They are comprised of perpendicular oscillating electric and magnetic fields that are in phase and are both mutually perpendicular to the direction of the velocity of the wave. It also turns out that visible light is an example of electromagnetic waves, but only represents a very small portion of the entire electromagnetic spectrum. The electromagnetic spectrum is commonly divided into seven regions: gamma rays, xrays, ultraviolet, visible, infrared, microwaves, and radio waves that vary inversely in terms of frequency and wavelength.

The last topics covered in the lesson involve the intensity of light as it propagates as a spherical wave and the Doppler Effect, both of which were applied to sound waves earlier in the course. The lesson is concluded with the solving of a few practice problems.

00:00 Lesson Introduction
01:10 Maxwell's Equations
06:30 Alternating Current Produces Electromagnetic Waves
08:38 Properties of Electromagnetic Waves
14:08 The Electromagnetic Spectrum
17:34 Light Intensity and the Doppler Effect
20:11 Electromagnetic Waves Practice Problems

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