A second harmonic has to be generated in a string of length l str… - Vidyadip

MCQ

A second harmonic has to be generated in a string of length $l$ stretched between two rigid supports. The points where the string has to be plucked and touched are respectively

✓
$\frac{l}{4}, \frac{l}{2}$
B
$\frac{l}{4}, \frac{3l}{4}$
C
$\frac{l}{2}, \frac{l}{2}$
D
$\frac{l}{2}, \frac{3l}{4}$

✓

Answer

Correct option: A.

$\frac{l}{4}, \frac{l}{2}$

a
(a)

In the $2^{\text {nd }}$ harmonic the shape of wave looks like.

The point of touching forms a node point of plucking forms an antinode. Hence, for $2^{\text {nd }}$ harmonic, we need to need wire touched at $\frac{l}{2}$ and pluck it at $\frac{l}{4}$.

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