http://www.ck12.org Chapter 19. Electromagnetism
FIGURE 19.13
James Clark Maxwell.- Light is an electromagnetic wave where oscillating electric and magnetic fields continuously give rise to one
another.
FIGURE 19.14
An electromagnetic wave propagating
through space.Maxwell’s determination that light was an electromagnetic wave involved a good deal of mathematics. But perhaps
he wasn’t entirely surprised with his result. Light, as we have discussed, has a definite speed, which is a fundamental
property of all wave phenomena, along with frequency and wavelength.
Since Maxwell’s work, electromagnetic waves with frequencies and wavelengths differing from visible light have
been detected. These waves have all the properties of visible light. They can be reflected and refracted, and they
can be focused, just like a magnifying glass focuses the sunlight. They can have wavelengths both much longer and
much shorter than visible light. The entire range of eletromagnetic waves is called theelectromagnetic spectrum,
Figure19.15.
http://demonstrations.wolfram.com/ElectromagneticWave/
As you can see from the figure, human vision is limited to a tiny part of the electromagnetic spectrum, with the
wavelength range of about 400 to 750 nm. We have, however, built instruments capable of detecting all segments
of the electromagnetic spectrum. Infrared goggles (also known as “night goggles”) work by detecting the heat