Answer: 2A cos(delta/2).
- A 2A
- B 2A cos(delta/2)
- C A cos(delta)
- D A cos(delta/2)
Correct answer: B. 2A cos(delta/2)
Explanation: Resultant amplitude = 2A cos(delta/2). For delta=0: 2A (constructive). For delta=pi: 0 (destructive).
A standing wave forms from two identical waves travelling in opposite directions and interfering; nodes (always zero displacement) and antinodes (maximum displacement) stay fixed in place, unlike a travelling wave where the whole pattern moves.
Concept context
Wave types, superposition, standing waves, Doppler effect, and sound intensity.