Question
A second harmonic has to be generated in a string of length $l$ stretched between two rigid supports. The point where the string has to be plucked and touched are
✓
Answer
To generate the second harmonic is a staring of length stretched between two rigid supports has to plucked at $l / 4$ and touched at $l / 2$
For second harmonic, wavelength $\left(\lambda_{2}\right)$ of the standing waves set up on the corresponds to the $n=2$
Thus, $\lambda_{n}=\frac{2 l}{n}$
$\Rightarrow \lambda_{2}=\frac{2 l}{2}=l$
This shows that we have an antinode at $l / 2$
This shows that we have an node at $l / 4$
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