Between the first and second critical angles, which waves are produced in the second material?

Between the first and second critical angles, which waves are produced in the second material?

• A. Both Transverse And Longitudinal Waves
• B. No Waves Are Produced
• C. Transverse Waves Only
• D. Longitudinal Waves Only

Answer: (C)

When a longitudinal wave reaches a boundary between two solids, the waves that can propagate into the second material depend on the incidence angle and the two possible modes in the second medium: a longitudinal (P) wave and a transverse (S) wave. There are two critical angles corresponding to these modes. In the angular range between these two critical angles, the condition for the P-wave to propagate in the second material is not met, so the P component becomes evanescent and cannot carry energy into the second material. At the same time, the S-wave transmission remains possible with a real transmission angle, so it does carry energy. As a result, the waves produced in the second material in this range are transverse (shear) waves only.

When a longitudinal wave reaches a boundary between two solids, the waves that can propagate into the second material depend on the incidence angle and the two possible modes in the second medium: a longitudinal (P) wave and a transverse (S) wave. There are two critical angles corresponding to these modes. In the angular range between these two critical angles, the condition for the P-wave to propagate in the second material is not met, so the P component becomes evanescent and cannot carry energy into the second material. At the same time, the S-wave transmission remains possible with a real transmission angle, so it does carry energy. As a result, the waves produced in the second material in this range are transverse (shear) waves only.