$A$ resistance of $20 \Omega$ is connected in the left gap of a metre bridge and an unknown resistance greater than $20 \Omega$ is connected in the right gap. When these resistances are interchanged,the balance point shifts by $20 \text{ cm}$. The unknown resistance is (in $\Omega$)

$A$ student obtained the following observations in an experiment of a meter bridge to find the unknown resistance of the circuit. The most accurate value of the unknown resistance is ............ $\Omega$.

$S.No.$	$R$	$l$	$100-l$	$S = \left( \frac{100-l}{l} \right)R$
$1$	$20\,\Omega$	$43$	$57$	$26.51\,\Omega$
$2$	$30\,\Omega$	$51$	$49$	$28.82\,\Omega$
$3$	$40\,\Omega$	$59$	$41$	$27.80\,\Omega$
$4$	$60\,\Omega$	$70$	$30$	$25.71\,\Omega$

In a meter bridge experiment for measuring an unknown resistance '$S$',the null point is obtained at a distance of $30 \ cm$ from the left side,as shown at point $D$. If $R$ is $5.6 \ k\Omega$,then the value of the unknown resistance '$S$' will be $\Omega$.

In a meter bridge experiment,the ratio of the left gap resistance to the right gap resistance is $2:3$. The balance length from the left end is (in $\,cm$)

The meter bridge shown is in a balanced position with $\frac{P}{Q} = \frac{l_{1}}{l_{2}}$. If we now interchange the positions of the galvanometer and the cell,will the bridge work? If yes,what will be the balance condition?

In a meter bridge,a $30 \Omega$ resistance is connected in the left gap and a pair of resistances $P$ and $Q$ in the right gap. Measured from the left,the balance point is $37.5 \text{ cm}$ when $P$ and $Q$ are in series,and $71.4 \text{ cm}$ when they are in parallel. The values of $P$ and $Q$ (in $\Omega$) are: