# Formula Condition for Constructive Interference Path difference Integer Wavelength

## Path difference

`$$ \Delta s $$`Unit

`$$ \mathrm{m} $$`

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

`$$ m $$`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

`$$ \lambda $$`Unit

`$$ \mathrm{m} $$`

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