Formula: Condition for Constructive Interference Path difference Integer Wavelength
$$\Delta s ~=~ m \, \lambda$$
$$\Delta s ~=~ m \, \lambda$$
$$m ~=~ \frac{ \Delta s }{ \lambda }$$
$$\lambda ~=~ \frac{ \Delta s }{ m }$$
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.