Why is that electrons radiate electromagnetic energy when they are accelerated?
An electromagnetic wave, as its name implies, consists of alternating electric and
magnetic fields, oriented at 90 degrees to each other, moving at the speed of light.
alternating fields sustain themselves because electricity (moving electric charges)
generates a magnetic field, and a changing magnetic field generates an electric field.
To demonstrate the first of these behaviors, hold a magnetic compass near a wire
a DC current. The compass needle will orient itself perpendicular to the wire as long as
current is flowing. Electric meters and motors both take advantage of this behavior.
To demonstrate the second behavior, plunge a magnet into a coil of wire connected to a
current measuring meter. As long as the magnet is moving, current will flow in the coil.
Electric generators take advantage of this behavior.
An electron carries an electric charge. A stationary electron creates no magnetic field.
(Like a wire with no current). An electron moving at constant velocity generates a steady
magnetic field, but (like a stationary magnet in a coil of wire) a constant
magnetic field won't result in another electric field. An electron moving with a CHANGING
velocity (ie. accelerating), however, generates a CHANGING magnetic field, which WILL
a changing electric field, which produces a changing magnetic field, etc. In other words,
it generates an electromagnetic wave.
Paul Walorski, B.A., Part-Time Physics Instructor
'The important thing is not to stop questioning. Curiosity has its own reason for existing. Never lose a holy curiosity.'