Answer: 3 dB.
- A 2 dB
- B 3 dB
- C 6 dB
- D 10 dB
Correct answer: B. 3 dB
Explanation: dB = 10 log(I/I<sub>0</sub>). If I doubles: delta dB = 10 log(2) = 10 x 0.301 = 3 dB.
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.