The resistances of the four arms $P, Q, R$ and $S$ in a Wheatstone's bridge are $10\,ohm$, $30\,ohm$, $30\,ohm$ and $90\,ohm$, respectively. The e.m.f. and internal resistance of the cell are $7\,volt$ and $5\,ohm$ respectively. If the galvanometer resistance is $50\,ohm$, the current drawn from the cell will be …………… $A$

The resistance per centimeter of a meter bridge wire is $\mathrm{r}$, with $\mathrm{X}\  \Omega$ resistance in left gap. Balancing length from left end is at $40 \mathrm{~cm}$ with $25\  \Omega$ resistance in right gap. Now the wire is replaced by another wire of $2 \mathrm{r}$ resistance per centimeter. The new balancing length for same settings will be at

Resistance are connected in a meter bridge circuit as shown in the figure. The balancing length $l_{1}$ is $40\,cm$. Now an unknown resistance $x$ is connected in series with $P$ and new balancing length is found to be $80\,cm$ measured from the same end. Then the value of $x$ will be $…….\Omega$

$A$ Wheatstone's bridge is balanced with a resistance of $625\, \Omega$ in the third arm, where $P, Q$ and $S$ are in the $1^{st}, 2^{nd}$ and $4^{th}$ arm respectively. If $P$ and $Q$ are interchanged, the resistance in the third arm has to be increased by $51\,\Omega$ to secure balance. The unknown resistance in the fourth arm is …………. $\Omega$

A resistance of $2\,\Omega $ is connected across one gap of a meter-bridge and unknown resistance, greater than $2\,\Omega $ , is connected a cross the other gap. When these resistances are interchanged, the balance point shifts by $20\ cm$ , neglecting any end correction, the unknown resistance is ……………. $\Omega$