JEE MAIN - Physics (2009 - No. 17)
Three sound waves of equal amplitudes have frequencies $$\left( {v - 1} \right),\,v,\,\left( {v + 1} \right).$$ They superpose to give beats. The number of beats produced per second will be :
$$3$$
$$2$$
$$1$$
$$4$$
Explication
Maximum number of beats $$ = \left( {v + 1} \right) - \left( {v - 1} \right) = 2$$