Answer: 4 Hz.
- A 2 Hz
- B 4 Hz
- C 6 Hz
- D 8 Hz
Correct answer: B. 4 Hz
Explanation: Beat frequency = |f<sub>1</sub> - f<sub>2</sub>| = |260 - 256| = 4 Hz. 4 beats per second heard.
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.