Two longitudinal waves have their compressions and rarefactions aligned, resulting in a larger amplitude. What is this phenomenon?

Two longitudinal waves have their compressions and rarefactions aligned, resulting in a larger amplitude. What is this phenomenon?

• A. Constructive interference
• B. Destructive interference
• C. Resonance
• D. Refraction

Answer: (A)

Constructive interference occurs when two longitudinal waves overlap so that their compressions align with each other and their rarefactions align as well. In this in‑phase overlap, the pressure fluctuations add together, producing a larger amplitude in the resulting wave. This is why the sound can seem louder where the waves reinforce each other. If the compressions lined up with the rarefactions, the amplitudes would partially cancel, giving a smaller amplitude—destructive interference. Resonance involves a system vibrating at its natural frequency and building up amplitude over time, which is a different situation, while refraction is the bending of waves when they move into a different medium.

Constructive interference occurs when two longitudinal waves overlap so that their compressions align with each other and their rarefactions align as well. In this in‑phase overlap, the pressure fluctuations add together, producing a larger amplitude in the resulting wave. This is why the sound can seem louder where the waves reinforce each other. If the compressions lined up with the rarefactions, the amplitudes would partially cancel, giving a smaller amplitude—destructive interference. Resonance involves a system vibrating at its natural frequency and building up amplitude over time, which is a different situation, while refraction is the bending of waves when they move into a different medium.