When two waves of almost equal frequencies n1 and n2 reach a point simultaneously, what is the time interval between successive maxima?

Hint: Use the concept of beats.
Step 1:Findthebeatfrequency.
Let,n1>n2
Beatfrequency,νb=n1-n2
Step 2:Findtheintervalbetweensuccessivemaxima.
Timeperiodofbeats=Tb=1νb=1n1-n2