The relationship between wavelength

, frequency f and speed of light c for an electromagnetic wave is

Using the data of the problem, we find
Answer:
Backwash effect
Explanation:
Your friend moved along the shore due to ; The swash effect and the Backwash effect
Swash effect is caused by the upsurge of water up along the slopping front of the beach and this same upsurge in water moves back into the beach in what is known as the backwash effect hence the movement of your friend form where they were in the surf zone to another position still within the surface zone is caused by the BACKWASH EFFECT
Explanation :
Antoine-Laurent Lavoisier reported four "element" classifications but included some substances that were combinations of elements rather than true elements in his listing.
He is also known as " father of modern chemistry". He gives the modern system of naming chemical substances. He also gives a theory for chemical reactivity of the oxygen.
A high electromagnetic wave has short, very fast, frequent waves.
a low electromagnetic wave has long, very slow, infrequent waves.
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