MCQ
For a particular resonance tube, following are four of the six harmonics below $1000 Hz$; $300,600,750$ and $900 \,Hz$. The two missing harmonics are
- A$75,150$
- ✓$150,450$
- C$400,800$
- D$250,400$
✓
Answer
Correct option: B.
$150,450$
b
(b)
(b)
The $6^{\text {th }}$ harmonic $\left(f_6\right)=\frac{6 v }{2 l}=900$
or $\frac{v}{2 l}=150$
Hence fundamental frequency of string $\frac{v}{2 l}$ or $150 \,Hz$ is missing.
$3^{\text {rd }}$ multiple of $150$ which is $450$ is also missing.
Hence required frequencies are $150,450$ .
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