Answer:
Constructive interference occurs when the phase difference between two coherent sources of light is an integer multiple of \( 2\pi \). Mathematically, this condition can be expressed as:
\[ \Delta \phi = 2m\pi \]
where \( \Delta \phi \) is the phase difference between the two sources, and \( m \) is an integer (\( m = 0, 1, 2, 3, \ldots \)).
- This means that the waves from the two sources are in phase or differ by a whole number of wavelengths (or multiples thereof), leading to constructive interference where the amplitudes of the waves add up.
In summary, constructive interference occurs when the phase difference \( \Delta \phi \) between two coherent sources of light is \( 2m\pi \), where \( m \) is an integer.
