What is an example of an electromagnetic radiation practice problem?

1 Answer
Apr 25, 2015

Background: Electromagnetic radiation moves at the speed of light in a vacuum. The speed of light, #c#, to three significant figures, is #3.00xx10^8"m/s"#. The relationship between wavelength, #lambda#, and frequency, #f#, is #c=lambda*f#.

Question: If the wavelength of a photon of red light is #725"nm"#, what is its frequency?

Answer:
Convert #725"nm"# to meters. (#1"m"=1xx10^9"nm"#)
#725 cancel"nm"xx(1 "m")/(1xx10^9 cancel"nm")=7.25xx10^(-7) "m"#

Rearrange #c=lambda*f# to solve for #f#.

#f=c/lambda = (3.00xx10^8 cancel("m")/s")/(7.25xx10^(-7) cancel(m)#= #4.14xx10^14 "/s"=4.14xx10^14 "Hz"#