To convert a galvanometer into a voltmeter,one should connect a

Which one of the following modifications may increase the sensitivity of a moving coil galvanometer?
$1^{st}$ Way: By using a spring of smaller torsion constant.
$2^{nd}$ Way: By using a smaller coil.
$3^{rd}$ Way: By using a stronger magnet.
$4^{th}$ Way: By using a coil having fewer number of turns.

In a moving coil galvanometer,a strong horse-shoe magnet with concave-shaped pole pieces is used to:

$A$ galvanometer with a resistance of $12 \,\Omega$ gives full-scale deflection when a current of $3 \, mA$ is passed. It is required to convert it into a voltmeter which can read up to $18 \, V$. The resistance to be connected is ............... $\Omega$.

$A$ moving coil galvanometer has $48$ turns and the area of the coil is $4 \times 10^{-2} \, m^2$. If the magnetic field is $0.2 \, T$,then to increase the current sensitivity by $25\%$ without changing the area $(A)$ and the magnetic field $(B)$,the number of turns should become:

When a resistance of $200 \Omega$ is connected in series with a galvanometer of resistance $G$,its range is $V$. To triple its range,a resistance of $2000 \Omega$ is connected in series. The value of $G$ is (in $\Omega$)