Question

Which of the following choices correctly describes the behavior of the sound wave as it moves from metal to air?

The sound wave slows down and refracts. The wavelength and frequency decrease.
The sound wave slows down and refracts. The frequency decreases, but the wavelength remains the same.
The sound wave does not change speed, but refracts. The wavelength decreases while frequency increases.
The sound wave slows down and refracts. The wavelength decreases, but the frequency remains the same.

If anyone could help me with this question, I would be really grateful.

Answer 1

The velocity (speed of sound) = frequency*wavelength.
When sound travels from one medium to another, the frequency does not change but the wavelength does and speed does. Read your choices. You know that A can't be right because BOTH f and w can't change, you know B can't be right because f can't change and C can't be right because v must change and f can't change. What does that leave? D says v is slower in air than metal, f does not change but w does. That suggests that D is the correct answer.