Most people realize that a rainbow is caused by sunlight shining on falling raindrops, but few people realize that (1) rainbows always appear low in the sky (never overhead), (2) they form circular arcs, and (3) they have colors arranged in a particular order. Some people are lucky enough to see a double rainbow, such as the one shown in the photograph here, but almost no one realizes that more than two rainbows can occur.

What determines why any particular rainbow looks the way it does?

The answer is in this chapter.

33-1   What Is Physics?

The information age in which we live is based almost entirely on the physics of electromagnetic waves. Like it or not, we are now globally connected by television, telephones, and the Web. And like it or not, we are constantly immersed in those signals because of television, radio, and telephone transmitters.

Much of this global interconnection of information processors was not imagined by even the most visionary engineers of 20 years ago. The challenge for today’s engineers is trying to envision what the global interconnection will be like 20 years from now. The starting point in meeting that challenge is understanding the basic physics of electromagnetic waves, which come in so many different types that they are poetically said to form Maxwell’s ...

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