Answer: 100 Hz.
- A 200 Hz
- B 100 Hz
- C 150 Hz
- D 400 Hz
Correct answer: B. 100 Hz
Explanation: A closed pipe supports only odd harmonics f, 3f, 5f. Consecutive resonances differ by 2f, so 500 - 300 = 200 = 2f, giving f = 100 Hz (harmonics 100, 300, 500).
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.