Question

Three S.H.M's of equal amplitude A and equal time period in the same direction combine. The difference in phase between each pair is ${60}^{\circ }$ ahead of the other. The amplitude of the resultant oscillation is :

• A. a
• B. 2a
• C. 0
• D. 4a

Answer 1

The correct option is B

2a

Resultant of first two with phase difference, $(\varphi ={60}^{\circ })$ will be $R_1=\sqrt{3a}$ with ${90}^{\circ }$ diffrence in phase with the third. The resultant of third and

$R_1$ is

$R=\sqrt{(\sqrt{3}a{)}^2+a^2}=2a$