5
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.
•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