Three waves of amplitudes 7 mm , 3 mm and 11 mm with a successive phase difference of π 2 are super -imposed. The amplitude of the resulting wave will be

Step-by-step solution

Let us say that the first wave has a zero phase, then the second one is ahead of the first by a phase of π 2 and so the third one is ahead of the first one by a phase of π . So the first and the third are opposite to each other. Hence, A r = ( 11 − 7 ) 2 + ( 3 ) 2 A r = 5 mm