Formula: Condition for Constructive Interference Path difference    Integer    Wavelength

Formula: Condition for Constructive Interference
Constructive Interference of Two Sine Waves

Path difference

The path difference of two waves, which travel to the observation point (e.g. to the point where a bright interference fringe can be seen). The path difference thus indicates by how many wavelengths a wave leads or lags another wave.

For constructive interference, the path difference takes the following values: \[ \Delta s ~=~ 0,~ \lambda,~ 2 \, \lambda,~ 3 \, \lambda, ~... \]


Integer multiple of the wavelength takes the following values in the case of constructive interference: \( m = 0, 1, 2, ... \). This integer indicates the factor by how much one wave precedes the other.


Wavelength of the two waves under consideration. So the wavelength of the light used.

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