Answer: doubles.
- A doubles
- B halves
- C becomes four times
- D is unchanged
Correct answer: A. doubles
Explanation: f ∝ 1/L, so halving the length doubles the frequency.
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.