Question 15. 5 You have learnt that a travelling wave in one dimension is represented by a function y = f (x, t) where x and t must appear in the combination x – v t or x + v t, i.e. y = f (x ± v t). Is the converse true? Examine if the following functions for y can possibly represent a travelling wave :(a) (x – vt )2 (b) log [(x + vt)/x0] (c) 1/(x + vt)Answer in ncert is c. Why?

No, the converse is not true. The basic requirement for a wave function to represent a travelling wave is that for all values of x and f, wave function must have a finite value. Out of the given functions for y only (iii) satisfies this condition. The other three functions (i), (ii) and (iv) cannot represent a travelling wave as the necessary condition is not satisfied by these functions