Question

Three waves of equal frequencies having amplitudes 10 mm, 4 mm and 7 mm arrive at a given point with successive phase difference of p/2. The amplitude of the resulting wave in mm is given by –

• A. 7
• B. 6
• C. 5
• D. 4

Answer 1

Answer: (C)

5

Answer 2

The resultant amplitude of first and third wave is = 10 – 7 = 3 mm

This wave now has a phase difference of p/2 with second wave. Hence, resultant amplitude.

a = $\sqrt{(3)^{2} + (4)^{2}}$= 5 mm