Answer:
Wavelength.
Explanation:
1 period, or wavelength, is measured from one crest to another or from one trough to another.
Answer:
Refraction is an effect that occurs when a light wave, incident at an angle away from the normal, passes a boundary from one medium into another in which there is a change in velocity of the light. The wavelength decreases as the light enters the medium and the light wave changes direction.
Explanation:
