If two waves interfere in such a way that their crests and troughs align to reinforce each other, what is this interference called?

If two waves interfere in such a way that their crests and troughs align to reinforce each other, what is this interference called?

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

Answer: (B)

When two waves meet with their peaks lining up with peaks and their troughs lining up with troughs, their amplitudes add together to create a larger overall wave. This reinforcement of the wave’s displacement is what we call constructive interference. It occurs because the disturbances from both waves are in the same direction at every point, so they amplify each other. If instead a crest meets a trough, the waves subtract from each other and can cancel out, producing a smaller amplitude or even no wave at all—that’s destructive interference. The other terms listed, frequencies and resonance, describe different ideas: frequencies are about how often the wave repeats per second, and resonance is about a system vibrating with a large amplitude at certain frequencies, not about how two waves combine. So the situation described—crests and troughs aligning to reinforce—is constructive interference, where the waves add up to produce a stronger effect.

When two waves meet with their peaks lining up with peaks and their troughs lining up with troughs, their amplitudes add together to create a larger overall wave. This reinforcement of the wave’s displacement is what we call constructive interference. It occurs because the disturbances from both waves are in the same direction at every point, so they amplify each other.

If instead a crest meets a trough, the waves subtract from each other and can cancel out, producing a smaller amplitude or even no wave at all—that’s destructive interference. The other terms listed, frequencies and resonance, describe different ideas: frequencies are about how often the wave repeats per second, and resonance is about a system vibrating with a large amplitude at certain frequencies, not about how two waves combine.

So the situation described—crests and troughs aligning to reinforce—is constructive interference, where the waves add up to produce a stronger effect.