Radiation From Point Charges

We are now going to investigate how the motion of point charges uses Faraday's law. We have seen that point charges moving with a constant velocity create a magnetic field. What happens if we accelerate a point charge?

The acceleration will change the magnetic field. From Faraday's law we know that a changing magnetic field will induce an electric field. What will be the properties of the induced electric field?

Before working on Faraday's law let's see if we can reason from common sense how the electric field will be affected.

Consider a point charge at rest as depicted below. We see the static inverse r squared Coulomb field from the charge. As the point charge begins to accelerate what will happen to the field?

The acceleration of the charge will create a disturbance in the field that will propagate outward from the charge at the speed of light. In the movie below, the charge stops accelerating a short time later and coasts with constant velocity thereafter. When the charge stops accelerating a Coulomb field again emerges.

What does the field look like inbetween the two circles?

Go to Exercise 2.


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