What is the resultant amplitude when two waves of the same frequency and identical phase are superposed?

Conditions

• The two waves have the same frequency.
• The two waves are in identical phase (phase difference is zero).

Reasoning, step by step

1. Identify the amplitudes of the two individual waves.
2. Verify that the waves have the same frequency and are in phase.
3. Add the two amplitudes together to find the resultant amplitude.

Example

In the video, a blue wave with amplitude $A=3$ and a red wave with amplitude $A=1$ are superposed. The resulting green wave has an amplitude equal to the sum of the individual amplitudes, which is 4.

Common misconceptions

• Believing that the amplitudes multiply instead of add.
• Assuming that the resultant wave will have a different frequency than the original waves.

Watch the explanation

Explore next

• What happens to the amplitude if the waves are exactly out of phase?
• How does the phase difference affect the resultant amplitude?