Which term describes a gradual change in wave direction due to varying depths?

• A. Wave Refraction
• B. Wave Diffraction
• C. Wave Frequency
• D. Wave Crest

Answer: (A)

Gradual change in wave direction due to varying depths is wave refraction. When waves move from deeper to shallower water, the portion still in deep water travels faster than the portion in shallow water. That difference in speed tilts the wave fronts, bending the waves so the crests align more parallel to the coastline as they approach shore. This bending is the essence of refraction. The other ideas don’t describe this depth-driven bending: diffraction is bending around obstacles or through openings, not because of depth changes; frequency is the rate at which waves pass a point and stays the same as waves move into shallower water; a crest is just the highest part of a wave, not a process of directional change.