Waves question for NEET / JEE Main, with solution

Answer: (D) Two identical waves travelling in opposite directions

Concept. A stationary wave forms when two waves of the same frequency and amplitude travel in opposite directions along the same line.

Step 1. Check the options. Waves of slightly different frequency in the same direction give beats; identical waves in the same direction just add. Only identical waves travelling in opposite directions form a stationary wave.

Answer. Two identical waves travelling in opposite directions (Option D).

Solution by Sreeraj P, M.Sc Physics