Question

Two radio stations that are 250 m apart emit sound waves of wavelength 100 m. Point A is 400 m from both station. Point B is 450m from both stations. Point C is 400 m from station $S_2$ and 450 m from station $S_1$. If the radio station emit sound waves in phase, which of the following statement is/are not true ?

• A. There will be destructive interference at A, B and C.
• B. There will be destructive interference at A and B, and constructive interference at C.
• C. There will be constructive interference at B and C, and destructive interference at A.
• D. There will be constructive interference at A and B, and destructive interference at C.

Answer 1

The correct option is D There will be constructive interference at A and B, and destructive interference at C.

At points A and B, the path difference between waves coming from two radio stations is zero, because both waves are in phase and the points are at same distances from both the stations, Hence there wiil be constructive interference at A and B.

For point C, path difference between the waves a 50 metres.
i.e.$\frac{\lambda }{2}$ so destructive interference takes places at point C.