Mass per unit length of the wire = µ =m/l.
Consider a small portion of the string of length dx at a distance x from the point of suspension O (Fig. 5.4). The tension at this point is (l – x) µg and the velocity of propagation of transverse wave at this point is
Time taken by the transverse wave to traverse a distance dx at this point is
Total time to travel the length of the wire is
