1. Wavelength is formally defined as the mean
distance between maximums (or minimums) of a
roughly periodic pattern and is normally measured in
micrometers (m) or nanometers (nm).
2. Frequency is the number of wavelengths that
pass a point per unit time. A wave that sends one
crest by every second (completing one cycle) is said
to have a frequency of one cycle per second, or one
hertz, abbreviated 1 Hz.