The reading of the voltmeter in the following circuit is ................ $V$.

$A$ potentiometer has a uniform potential gradient across it. Two cells connected in series $(i)$ to support each other and $(ii)$ to oppose each other are balanced over $6 \ m$ and $2 \ m$ respectively on the potentiometer wire. The ratio of the $e.m.f.$s of the cells is:

If the length of a potentiometer wire is increased,then the length of the previously obtained balance point will

In an experiment to measure the internal resistance of a cell by a potentiometer,it is found that the balance point is at a length of $2\,m$ when the cell is shunted by a $5\,\Omega$ resistance; and is at a length of $3\,m$ when the cell is shunted by a $10\,\Omega$ resistance. The internal resistance of the cell is,then ................ $\Omega$.

In a potentiometer experiment, a null point is obtained at a particular point for a cell on a potentiometer wire of length '$x$' cm. If the length of the potentiometer wire is increased by a few cm without changing the cell or the driving source, the balancing length will:

In the given arrangement,$E_1 = 5 \, V$ and $E_2 = 7 \, V$. The balancing length is $6 \, m$. If the terminals of $E_2$ are reversed,then the new balancing length will be: