Question

Which of the following statements is correct for stationary waves
A. Nodes and antinodes are formed in case of stationary transverse wave only
B. In case of longitudinal stationary wave , compressions and rarefactions are obtained in place of nodes and antinodes respectively
C. Suppose two plane wave , one longitudinal and the other transverse having same frequency and amplitude are travelling in a medium in opposite directions with the same period , by superposition of these waves , stationary waves cannot be obtained
D. None of the above

Answer 1

Correct Answer - C
Node means a point at which medium particles do not displace from its mean position and antinode mean a point at which particles oscillate with maximum possible amplitude . Nodes and antinodes are obtained for both types of stationary waves , transverse and longitudinal . Hence , options (a) and (b) both are wrong . To obtain a stationary wave , two waves travelling in opposite directions , having same amplitude , same frequency are required . They must have same nature , means either both of the waves should be longitudinal or both of them should be transverse . Hence , option ( c) is correct .