NCERT · Class 12 · Physics · Wave OpticsWhat is the condition for constructive interference in terms of path difference?

The condition for constructive interference in terms of path difference between two interfering light waves is that the path difference delta must be an integral multiple of the wavelength lambda. Mathematically, it is expressed as delta = n * lambda, where n takes integer values such as 0, 1, 2, 3, and so on. When this condition is fulfilled, the waves arrive in phase, reinforcing each other to produce maximum brightness.