Frequency

Frequency is a property of an oscillation, vibration, or other regularly-repeating phenomenon. The frequency of such a phenomenon is the number of repetitions in a unit time. In the SI system of units, frequency is measured in Hertz (Hz), the number of repetitions in one second.

Frequency is inversely proportional to wavelength, which is a length measurement. :$\lambda ={\frac {c}{f}}\,\!$ ,

$E=hf\,\!$ ,

where c = 299,792,458 m/s (the speed of light) and h = 6.626 x 10^-34 Js (Planck's constant)