If two waves have the same phase and frequency, their superposition results in which type of interference?

If two waves have the same phase and frequency, their superposition results in which type of interference?

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

Answer: (B)

When two waves superpose, you add their displacements at every point. If they share the same phase, their peaks align with peaks and troughs align with troughs, so their amplitudes reinforce each other. That means the resulting wave has a larger amplitude than either wave alone, which is constructive interference. If the amplitudes are equal, the total amplitude can double; in general, it’s the sum of the two amplitudes. Resonance is a different idea involving a system’s natural frequency, and interference is the broad phenomenon, but the in-phase, same-frequency case specifically yields constructive interference.

When two waves superpose, you add their displacements at every point. If they share the same phase, their peaks align with peaks and troughs align with troughs, so their amplitudes reinforce each other. That means the resulting wave has a larger amplitude than either wave alone, which is constructive interference. If the amplitudes are equal, the total amplitude can double; in general, it’s the sum of the two amplitudes. Resonance is a different idea involving a system’s natural frequency, and interference is the broad phenomenon, but the in-phase, same-frequency case specifically yields constructive interference.