Question
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?
Solution
Superposition principle is in accordance with the linear character of the differential equation governing wavemotion. If, y1 and y2 are solutions of the wave equation, then any linear combination of y1 and y2 is also a solution of the wave-equation. When amplitudes are large (e.g., high intensity laser beams) and non-linear effects are important, the situation is for more complicated.
