Question

Two waves having the same amplitude and frequency overlap near a point. The ratio of the intensities when the two waves arrive in phase to that when they arrive 90° out of phase is ______ 

Options

• 1 : 1

• `sqrt2 : 1`

• 2 : 1

• 4 : 1

Answer 1

Two waves having the same amplitude and frequency overlap near a point. The ratio of the intensities when the two waves arrive in phase to that when they arrive 90° out of phase is 2 : 1.

Explanation:

When they arrive in phase, the resultant amplitude = 2a

For a phase difference of `pi/2,` R = `[a^2 + a^2]^{1/2}`

= `sqrt2a`

∴ `I_1/I_2 = (4a^2)/(2a^2) = 2/1`