Video: Calculating Wavelength

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Calculating Wavelength

 
Here’s a diagram of a wave in a rope. You know the length of the rope. How do you determine the wavelength? The process involves three steps.
 
First, count the number of waves in the rope. Start at the beginning and trace over the pattern with your finger to count the number of waves. I like to count the number of half-waves as shown in the animation. I’ve counted seven half-waves or 3.5 waves.
 
Second, write an equation relating the rope length (L), the wavelength (l), and the number of waves. Within the length of rope (L), there is 3.5 wavelengths (l). So write:  7.0 = 3.5 • l. The Greek letter “lamda” represents the wavelength.
 
Third, solve your equation for wavelength (l) . Manipulate the equation to get lambda by itself. Divide both sides by 3.5. The 3.5 cancels from the right side and shows up in the denominator on the left side. So wavelength is 7.0 divided by 3.5. That’s 2.0 meters. You're done!
 
To summarize:
1.   Count the number of waves.
2.   Write an equation relating the rope length, wavelength , and the number of waves.
3.   Solve the equation for wavelength.
 
I'm Mr. H, letting you know … You got this!


 
 

 

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