For teachers, one of best things about light is that it is cheap. Students can make rainbows. They can learn why mixing red, green, and blue pigment makes black paint, whereas mixing red, green, and blue light makes white light. They can learn not only about light, but also about the methods of science. In the last 50 years, new instruments, such as radio telescopes and ultraviolet detectors, have become our seeing-eye dogs outside that window.
Electromagnetic radiation is one of the many forms that energy can take.
Like runners in a three-legged race, the two fields are locked together. Together they urge each other on, radiating, or traveling, through space. Like runners, the fields vary in strength. They weaken, then regain strength, then weaken again, and so on. When the electric field is strongest, so is the magnetic.