Answer the following questions :
(a) When a low flying aircraft passes overhead, we sometimes notice a slight shaking of the piture on our TV screen. Suggest a possible expanation.
(b) As you have learnt in the text, the principle of linear superposition of wave displacement is basic to understanding intensity distributions in diffractions and interference patterns. What is the justification of this principle ?

Explanation

Superposition principle follows from the linear character of the (differential) equation governing wave motion. If `y_(1) and y_(2)` are solutions of the wave equation, so is any linear combination of `y_(1) and y_(2)` . When the amplitudes are large (e.g., high intensity laser beams) and non-linear effects are important, the situation is far more complicated and need not concern us here.