Skip to main content

Formula Condition for constructive interference Path difference    Integer    Wavelength

Formula
Formula: Condition for constructive interference
Constructive Interference of Two Sine Waves
Hover the image! Get this illustration

Path difference

Unit
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

Unit
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

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