Answer: 1/r2.
- A r
- B 1/r
- C 1/r2
- D 1/r3
Correct answer: C. 1/r2
Explanation: Sound intensity follows inverse square law: I proportional to 1/r2 (energy spreads over 4*pi*r2).
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.