c = λf

where:

* c is the speed of light (approximately 299,792,458 meters per second in a vacuum)

* λ (lambda) is the wavelength (measured in meters)

* f is the frequency (measured in Hertz, Hz)

This equation tells us:

* The speed of light is constant.

* Wavelength and frequency are inversely proportional. This means that as the wavelength increases, the frequency decreases, and vice versa.

Rearranging the equation, you can find:

* λ = c / f (to calculate wavelength if you know the speed of light and frequency)

* f = c / λ (to calculate frequency if you know the speed of light and wavelength)