Answer: 4.
- A 2
- B 4
- C 8
- D 516
Correct answer: B. 4
Explanation: Beat frequency = |260 − 256| = 4 beats per second.
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.