Answer the following question:

As you have learnt in the text, the principle of linear superposition of wave displacement is basic to understanding intensity distributions in diffraction and interference patterns.

What is the justification of this principle?

The linear superposition describes the linear character and solutions of the differential equation that governs the wave motion. The intensity distributions in both diffraction and interference patterns require the linear superposition to deduce and characterize the wave equation. If we take X1 and X2 as the displacement covered by the two waves. We can infer the resultant displacement of the two waves given as, X = X1 + X2