# Q10.20 (b)  Answer the following questions: 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 superposition principle comes from the linear character of the differential equation of wavemotion.that is if $x_1$ and $x_2$ are the solution of any wave equation, then linear combination of  $x_1$ and $x_2$ is also the solution of the wave equation.