Amplitude Physics Example 2

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Example 2

medium
Two identical waves with amplitude A=3 cmA = 3 \text{ cm} overlap perfectly in phase. What is the resulting amplitude? What if they are perfectly out of phase (shifted by half a wavelength)?

Solution

  1. 1
    When two waves are perfectly in phase (constructive interference), amplitudes add: Aresult=A+A=2A=6 cmA_{\text{result}} = A + A = 2A = 6 \text{ cm}.
  2. 2
    When perfectly out of phase (destructive interference), amplitudes cancel: Aresult=A−A=0 cmA_{\text{result}} = A - A = 0 \text{ cm}.
  3. 3
    In general, the resulting amplitude depends on the phase difference between the waves.

Answer

In phase: 6 cm;Out of phase: 0 cm\text{In phase: } 6 \text{ cm}; \quad \text{Out of phase: } 0 \text{ cm}
The superposition principle states that when waves overlap, their displacements add algebraically. In-phase waves reinforce each other (constructive interference), while out-of-phase waves cancel (destructive interference).

About Amplitude

The maximum displacement of a wave from its equilibrium (rest) position, measuring the wave's strength or intensity.

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