Q.15.5 (b) You have learnt that a travelling wave in one dimension is represented by a function  where 
 and 
 must appear in the combination
 or 
, i.e. 
. Is the converse true?  Examine if the following functions for y can possibly represent a travelling wave :
 
                
                  No, the given function cannot represent a travelling wave because as x and t become zero the given function won't be converging to a constant value and therefore the converse is not true.