Question
For sound waves, if the number of nodes for the 5^ th harmonic of an open-ended pipe is n and that for the 9^ th harmonic of the same pipe with one of its ends closed is m, the ratio n m is :
NEET
Physics
Waves and Sound
2026
NEET 2026 (Re-NEET)
NEET Physics Question (2026) — Solution
Options
- A. 3 5
- B. 5 9
- C. 9 5
- D. 1
Answer
D. 1
Step-by-step solution
For an open-ended pipe, the p^ th harmonic contains p nodes and p+1 antinodes. For the 5^ th harmonic of the open-ended pipe, the number of nodes is n = 5. For a pipe closed at one end, only odd harmonics are present. The q^ th harmonic (where q is an odd integer) contains q+1 2 nodes and q+1 2 antinodes. For the 9^ th harmonic of the closed pipe, the number of nodes is m = 9+1 2 = 5. The ratio of the number of nodes is n m = 5 5 = 1.
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