The subtraction of wave energy as waves interact, producing smaller waves is known as what?

• A. Constructive Interference
• B. Destructive Interference
• C. Reflection
• D. Interference

Answer: (B)

Waves interact through superposition: when two waves meet, their displacements add together. If they are opposite in phase, the crest of one meets the trough of the other and the amplitudes subtract, producing a smaller resultant wave. This is destructive interference. Energy isn’t actually destroyed; it’s redistributed, with cancellation occurring at some points and reinforcement at others if the waves are not perfectly out of phase. In contrast, when waves are in phase, their amplitudes reinforce each other to produce larger waves (constructive interference). Reflection is about a wave bouncing off a boundary, not the general cancellation of waves. Interference is the broad phenomenon, but the description of producing smaller waves specifically points to destructive interference.