Final answer:
Wavelength is measured from crest to crest or trough to trough, represented by the Greek letter lambda, and measured in units of length.
Step-by-step explanation:
The measurement of wavelength is done by measuring the distance between two consecutive similar points along the wave.
This could be from crest to crest or from trough to trough.
The wavelength is typically represented by the Greek letter lambda (λ) and can be measured in any unit of length like meters or centimeters.
The consistent distance between these points is due to the periodic nature of waves, meaning each cycle of the wave pattern repeats itself identically.