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Radiant energy, called "electromagnetic radiation", is released every time
an electron slows down, changes its orbit around an atom or vibrates
back and forth. Through these changes in its motion, the electron creates
a changing electric field. It is an observed fact that when an electric
field is changing, a magnetic field appears. And when
a magnetic field is changing, an electric field appears. This is how
an electromagnetic wave works and how it is able to travel immense distances
from faraway stars to our small solar neighborhood. The wave's changing
electric field produces a changing magnetic field which in turn creates another
changing electric field and on and on and on.
If you observe the electric and
magnetic fields as
the wave passes by, you will note that the size of the fields go up and down
again and again. The distance in space between peaks in the field is
called the "wavelength". The number of peaks that a non-moving observer
counts per second as the wave passes by is called the "frequency".
The electric and magnetic fields in the wave point in directions that
are 90 degrees apart and both fields point 90 degrees away
from the direction the wave is moving.
The most familiar form of radiant energy is visible light.
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