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Light is an electromagnetic wave
•Changing electric fields generates magnetic fields
•Changing magnetic fields generates electric fields
•Can set up a cycle where one field causes the other:
–The E and B fields oscillate in strength, and the disturbance moves forward.
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•To describe the wave you need to specify
–Direction it is moving
–Strength of the fields (its intensity)
–Frequency or Wavelength of the oscillation (u and l are inversely related)
–Orientation of the electric E field:  up or sideways (polarization)
•You do not need to specify its speed
–In a vacuum all lightwaves move at the same speed c = 3´108 m/s
From our text:  Horizons, by Seeds