It is an important observation that all electromagnetic radiation,
radio waves through gamma rays, moves at the same universal speed.
This is the speed of light, c = 3 x 10
or 30,000,000,000 centimeters per second. For any such radiation
we can write
=
c = 3 x 10
cm .


Because the speed of light is constant, if we know either the frequency
or the wavelength of electromagnetic radiation we can calculate
the other quantity.
