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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?

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#### Solution

The principle of linear superposition of wave displacement is essential to our understanding of intensity distributions and interference patterns. This is because superposition follows from the linear character of a differential equation that governs wave motion. If y_{1} and y_{2} are the solutions of the second-order wave equation, then any linear combination of y_{1} and y_{2 }will also be the solution of the wave equation.

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