Two sound sources emitting sound each of wavelength `lambda` are fixed at a given distance apart. A listener moves with a velocity `u` along the line joining the two suorces. The number of beats heard by him per second is

A and B are two identical sound sources cachemitting a note of frequency 1000 Hz. A person moves from A to B along the line joining the two sources. How fast should be move to that he has 7 beats per second. velocity of sound 330 m/s ?

There are three sources of sound of equal intensity with frequencies 400, 401 and 402 vib/sec . The number of beats heard per second is

There are two sources of sound of equal intensity with frequencies 400Hz and 408Hz are vibrated together. The number of beats heard per second is

Two sources P and Q produce notes of frequency 660 Hz each. A listener moves from P to Q with a speed of 1 ms^(-1) . If the speed of sound is 330 m//s , then the number of beats heard by the listener per second willl be