Question

In Melde's experiment, the string vibrates in seven segments under tension of $9gm-wt$. If string is to be vibrated in three segments then the tension required will be

• A. $1.4gm$-$wt$
• B. $13gm$-$wt$
• C. $49gm$-$wt$
• D. $61gm$-$wt$

Answer 1

Answer: (C)

$49gm$-$wt$

The frequency is the same before and after changing the Tension and the number of loops.

From the formula $f=\frac{n}{2L}\sqrt{\left(T/m\right)}$, we get

$\frac{7}{2L}\sqrt{\left(9/m\right)}=\frac{3}{2L}\sqrt{\left(T^{\prime }/m\right)}$

=>$T^{\prime }=49gm-wt$