question_answer 20)

Answer the following questions : (a)When a low flying aircraft passesoverhead, we sometimes notice a slightshaking of the picture on our TV screen. Suggest a possible explanation. (b)As you have learnt in the text, theprinciple of linear superposition of wavedisplacement is basic to understandingdistributions in diffraction and interferencepatterns. What is the justification of thisprinciple ?  

Answer:

(a) When a low flying air craft passesoverhead, the metallic body of the air craftreflects the TV signal. A slight shaking ofthe picture on the TV screen takes placedue to the interference of the reflectedsignal from the air craft and the directsignal received by the antenna. (b) The linear combination of waveequations is also a wave equation. This isthe very basis of the superpositionprinciple.