How to Calculate a Wave Length

In physics, the length of a sinusoidal wave is a measure of the distance between each complete cycle of the wave. The wavelength is represented by the distance between consecutive crests or troughs along the length of the wave. The wavelength can be calculated using the frequency of the wave and the speed of propagation of the wave, which is a property of the medium through which the wave is traveling. If, as is the case with a typical physics problem, you are calculating the length of a wave in a vacuum, you can use the speed of light, 299,792,458 meters per second, as the speed of propagation.

Things You'll Need

• Calculator

Instructions

1. Plug the velocity of propagation for the wave being measured into the following equation: frequency x wavelength = velocity of propagation. Ensure that the values of the velocity are represented in meters per second. For example, to measure the wavelength of a radio wave with a frequency of 3X10^8 Hz in a vacuum you should use 299,792,458 meters per second, the speed of light, as the velocity of propagation.

2. Plug the frequency of the wave, in hertz (Hz), into the equation. The frequency of a wave is set by the force that is driving the oscillation in the medium. A single hertz is equal to 1 wave per second. The frequency in the example is 3X10^8 Hz.

3. Divide both sides of the equation by the frequency. The result of dividing the velocity of propagation by the frequency is equal to the wavelength. Divide the speed of light by the frequency in the example to find the radio wave has a wavelength of about 0.999 meters.

References

• Davidson College Wep Physics: Frequency, Wavelength, and Velocity
• University of California, Santa Cruz: Wavelength, Period, and Frequency
• Brigham Young University: Frequency to Wavelength Calculator
• The National Institute of Standards and Technology: Fundamental Physical Constants
• The University of Tennessee: The Electromagnetic Spectrum