The concepts of coherent addition and incoherent addition of waves are fundamental in wave
physics,
particularly when analyzing interference and superposition phenomena.
1. Coherent Addition of Waves
- Definition: Coherent addition occurs when waves have a constant phase relationship. This
means
the relative phase difference between the waves does not change over time.
- Conditions:
- Waves must have the same frequency (or very close frequencies).
- The phase difference between the waves is constant.
- Result:
- The superposition of such waves results in constructive or destructive interference,
depending on their phase difference:
* Constructive interference: When the waves are in phase (phase difference = 0° or multiples
of 360°), their amplitudes add up.
A_resultant = A1 + A2
* Destructive interference: When the waves are out of phase (phase difference = 180°),
their amplitudes partially or completely cancel.
A_resultant = A1 - A2
- Example:
- Laser beams (which are coherent light sources) interfering in a double-slit experiment.
2. Incoherent Addition of Waves