Question

I observe a wave traveling in medium A at velocity V_A as it reflects against a boundary with medium B. The reflected wave is inverted, or, equivalently, phase-shifted by ±π, and is smaller in amplitude than the initial wave. Some wave in transmitted and travels at V_B in medium B.
What can I conclude about V_B?

1. Not enough information is provided to answer the question.

2. VB is infinity.

3. 0 < VB < VA

4. VB = 0

5. VA < VB < infinity.

Answer 1

Solution

Answer:

The reflection coefficient at an interface is given by,

When the reflected wave is inverted or possess a +/- pi phase difference relative to incident wave, value of reflection coefficient is negative. ie,

Since the wave should have a nonzero velocity in both media, they must be greater than zero. Hence correct answer is option 3.