Question

Answer the following questions:
(a) When a low flying aircraft passes overhead, we sometimes notice a slight shaking of the picture on our TV screen. Suggest a possible explanation.
(b) 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?

Answer 1

Here we have to examine each statement separately and then observe the possible explanations for the statement. In the first statement we have to apply the concept of radar and in the second statement we have to apply the principle of superposition.

Complete step by step answer:
(a) The TV signals obtained by the antenna will interfere with weak radar signals transmitted by a low-flying aircraft. As a consequence, television signals can get blurred. Therefore, as a low-flying plane flies overhead, we often find the image on our television screen moving slightly.
(b) For our interpretation of intensity distributions and interference patterns, the concept of linear superposition proceeds from a differential equation’s linear character that governs wave motion.

Additional information:
Multipath airplanes are caused by bouncing the OTA signal across certain objects, such as damp or frozen objects, houses or a moving aeroplane. Any hilly landscapes and trees can cause problems. Moving the antenna a few feet will also help mitigate the issue.
The theory of superposition can be extended to waves as two (or more) waves pass through the same medium concurrently. Without being interrupted, the waves flow through one another. At any point in space or time, the net displacement of the medium is precisely the sum of the actual wave displacements.

Note: Here in the first case we have to see whether the aircraft is flying low or high.
For the second case we can say that the superposition theorem is important because it simplifies the discovery of solutions to complex linear problems and because many of the basic laws of physics are linear.