### Calculating wavelength

Posted:

**Sun Apr 15, 2018 11:49 pm**How would you arrange the formula to calculate wavelength when the frequency of light is given?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=14&t=30829

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Posted: **Sun Apr 15, 2018 11:49 pm**

How would you arrange the formula to calculate wavelength when the frequency of light is given?

Posted: **Sun Apr 15, 2018 11:58 pm**

You would use the equation c=wavelength x frequency. Therefore you would divide the speed of light or c by the given frequency to find wavelength.

Posted: **Mon Apr 16, 2018 3:41 pm**

The attached image is helpful in visualizing the relationship between 'c', wavelength, and frequency. The bottom parts of the pyramid 'wavelength' and 'frequency' multiply to equal the top value 'speed of light', and the top value can divide by either bottom value to get the other bottom value

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source:

https://www.youtube.com/watch?v=tIxqRSUDG6s

"Wavelength Frequency Equation" by Marie Stott (2012)

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source:

https://www.youtube.com/watch?v=tIxqRSUDG6s

"Wavelength Frequency Equation" by Marie Stott (2012)

Posted: **Mon Apr 16, 2018 9:23 pm**

The basic equation c = fλ can be arranged as you would rearrange an equation in math. By moving around the variables you are keeping the equation the same, but making it easier to select for the unknown value you are trying to find.

For instance, if I want to find the frequency of a wave I would use:

f = c/λ frequency (Hz) = wave speed (m.s-1) / wavelength (m)

Note that the units cancel out to leave s-1, which is equal to Hz (the cycles per second that occur).

Similarly, if I want to find the wavelength I would use:

λ = c/f

For instance, if I want to find the frequency of a wave I would use:

f = c/λ frequency (Hz) = wave speed (m.s-1) / wavelength (m)

Note that the units cancel out to leave s-1, which is equal to Hz (the cycles per second that occur).

Similarly, if I want to find the wavelength I would use:

λ = c/f

Posted: **Mon Apr 16, 2018 9:26 pm**

Is there ever a time we would look for a speed other than that of light? Or does this equation only ever use c?