Answer: 100 Hz.
- A 900 Hz
- B 100 Hz
- C 150 Hz
- D 600 Hz
Correct answer: B. 100 Hz
Explanation: For a string the harmonics are f, 2f, 3f, ... The third harmonic is 3f = 300 Hz, so the fundamental f = 100 Hz.
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.