Electromagnetic waves

In the idealized example illustrated in Figure 10.23 the current is switched on suddenly and just once. In practice such a single sharp pulse has little significance. More interesting and relevant is the effect of a periodically alternating source of current giving rise to an electromagnetic wave.

E field

E field

B field

Figure 10.24 Electromagnetic wave.

B field

Figure 10.24 Electromagnetic wave.

The electric and magnetic fields are perpendicular to one another. They change continously oscillating in phase at right angles to the direction of propagation. In the diagram above a source charge oscillates along the y axis. The E field also oscillates along the y direction while the B field vectors always point along the z axis.

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