Chapter 11. Light

11.1. Light

Light is an electromagnetic wave, a traveling disturbance of varying electric and magnetic fields.

The velocity of light waves in a vacuum is c = 2.99792458 × 108 ms−1.

Figure 11.1 describes any type of wave, including light waves.

Figure 11.1

For visible light, the frequency is on the order of 1015 Hz. Photodetectors cannot respond to such rapid changes and thus generally indicate rms or mean values of power of the radiation.

Light can also be regarded as a stream of photons, individual particles of zero mass with an energy as in Figure 11.2.

Figure 11.2

The energy of a photon depends on the frequency but ...

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