The interference of a pair of in-phase waves results in a single wave of greater amplitude than either of its components. This combination is called

• A. Interference
• B. Destructive interference
• C. Constructive interference
• D. Diffraction

Answer: (C)

When two waves meet, their disturbances add together in a process called superposition. If they are in phase—crests line up with crests and troughs with troughs—their amplitudes reinforce each other. This makes a single resulting wave with a larger amplitude than either of the original waves. That situation is called constructive interference.

Interference, in general, is the overall phenomenon of waves overlapping and affecting each other. Destructive interference is the opposite case, where the waves are out of phase and partially or fully cancel each other, reducing amplitude. Diffraction is the bending of waves around obstacles or through openings, not the simple addition of amplitudes.