A and B are two sources generating sound waves. A listener is situated at C . The frequency of the source at A is 500 ~Hz . A, now, moves towards C with a speed 4 ~m / s . The number of beats heard at C is 6 . When A moves away from C with speed 4 ~m / s , the number of beats heard at C is 18 . The speed of sound is 340 ~m / s . The frequency of the source at B is :

Step-by-step solution

f =500 ~Hz Case 1: When source is moving towards stationary listener apparent frequency ^ = ( v v - v _ s ) =500 ( 340 336 )=506 ~Hz Case 2 : When source is moving away from the stationary listener ^ = ( v v + v _ s )=500 ( 340 344 )=494 ~Hz In case 1 number of beats heard is 6 and in case 2 number of beats heard is 18 therefore frequency of the source at B =512 ~Hz