When a sound wave goes from air into water, the quantity that remains unchanged is its
A) speed.
B) amplitude.
C) frequency.
D) wavelength.

Question

Quizplus · Accepted Answer

When a sound wave passes through a boundary between two mediums with different densities (like air and water), the speed of the wave changes in accordance with the equation v = fλ (where v is speed, f is frequency, and λ is wavelength). Since the speed changes, either the frequency or the wavelength (or both) must also change to maintain this equation. In this case, the frequency remains unchanged while the wavelength decreases (since the speed of sound is faster in water than in air). Therefore, choice C is correct while choices A, B, and D are incorrect.

When a Sound Wave Goes from Air into Water, the Quantity