Question

Two monochromatic sources of electromagnetic wave, P and Q emit waves of wavelength $\lambda =20m$ and separated by $5m$ as shown. A, B and C are three points where interference of these waves is observed. If phase of a wave generated by P is ahead of wave generated by Q y $\frac{\pi }{2}$ then (given intensity of both waves is I):

• A. phase difference of these waves at B is ${180}^{\circ }$
• B. intensities at A, B and C are in the ratio 2 : 0 : 1 respectively.
• C. intensities at A, B and C are in the ratio 1 : 2 : 0 respectively.
• D. phase difference at A is $0^{\circ }$

Answer 1

The correct option is C intensities at A, B and C are in the ratio 1 : 2 : 0 respectively.

When $Q>\frac{\pi }{2}$ then intensities at $A,B$ and $C$ are in the ratio $1:2:0$ respectively.