When two waves are in-phase at a point, what is typically observed in the resultant wave?

When two waves are in-phase at a point, what is typically observed in the resultant wave?

• A. The amplitude increases due to constructive interference.
• B. The amplitude decreases.
• C. The frequency changes.
• D. The wavelength changes.

Answer: (A)

When two waves meet with zero phase difference at a point, their displacements add together. This constructive interference causes the resultant wave to have a larger amplitude, equal to the sum of the individual amplitudes. If both waves have the same frequency, the resultant is a sinusoid with the same frequency and wavelength, but with increased amplitude (and thus higher intensity, since intensity scales with amplitude squared). In other words, the peaks align and reinforce each other, boosting the signal at that location.

When two waves meet with zero phase difference at a point, their displacements add together. This constructive interference causes the resultant wave to have a larger amplitude, equal to the sum of the individual amplitudes. If both waves have the same frequency, the resultant is a sinusoid with the same frequency and wavelength, but with increased amplitude (and thus higher intensity, since intensity scales with amplitude squared). In other words, the peaks align and reinforce each other, boosting the signal at that location.