Two waves of equal amplitude and frequency interfere each other. The ratio of intensity when the two waves arrive in phase to that when they arrive `90^@` out of phase is

Options

A. `1:1`
B. `sqrt(2):1`
C. `4:1`
D. `2:1`

Answer

D

Explanation

When they arrive in phase, the resultannt amplitude=2a
for a phase difference of `pi/2,R=[a^(2)+a^(2)]^(1//2)=sqrt(2)a`
`therefore (I_(1))/(I_(2))=(4a^(2))/(2a^(2))=(2)/(1)`