University of Wisconsin Green Bay

Variations in the electric field of a light wave are shown in the graph below. What is the wavelength of the wave?

  • In this case, you are given information about the period (and therefore frequency) of a wave and asked for the wavelength of that same wave. Frequency and wavelength are very closely related and so this is just a definition problem.

  • A picture representing the wave properties is already provided. No further picture is necessary.

  • Wavelength and frequency are closely related quantities, and the relationship is given through the wave equation:

  • The wavelength of this light wave is 6000 nm.

  • As long as you recognize that period and frequency are inverses of each other, and that they are closely related to the wavelength of a wave, this is a straightforward single-step problem. Be careful not to assume that the graph shows wavelength directly--make sure to always read the axis.

    Visible light has wavelengths from about 400 to 700 nm. This is a longer wavelength. If you check the electromagnetic spectrum, you will see that this is in the infra-red range.