$A$ voltmeter has a range $0-V$ with a series resistance $R$. With a series resistance $2R$,the range is $0-V'$. The correct relation between $V$ and $V'$ is

$A$ galvanometer whose resistance is $120 \, \Omega$ gives full-scale deflection with a current of $0.05 \, A$. To enable it to read a maximum current of $10 \, A$,a shunt resistance is added in parallel with it. The resistance of the ammeter so formed is .............. $\Omega$.

The graph which represents the relation between the total resistance $R$ of a multi-range moving coil voltmeter and its full-scale deflection $V$ is

$A$ galvanometer has a current range of $10 \text{ mA}$ and a voltage range of $0.75 \text{ V}$. To convert this galvanometer into an ammeter of range $10 \text{ A}$, what is the shunt resistance?

Write the equation for the series resistance required to increase the voltage range of a galvanometer by a factor of $n$.

$A$ voltmeter of resistance $R$ is to be used to measure the potential difference across a resistance $r$. In which case will the reading be nearest to the actual potential difference in the absence of the voltmeter?