When a $12\,\Omega$ resistor is connected in parallel with a moving coil galvanometer,its deflection reduces from $50$ divisions to $10$ divisions. The resistance of the galvanometer is ............. $\Omega$.

Assertion : The sensitivity of a moving coil galvanometer is increased by placing a suitable magnetic material as a core inside the coil.
Reason : Soft iron has high magnetic permeability and cannot be easily magnetized or demagnetized.

The range of an ammeter of resistance $G$ can be increased from $I$ to $nI$ by connecting

Two tangent galvanometers $A$ and $B$ are identical except in their number of turns. They are connected in series. On passing a current through them,deflections of $60^{\circ}$ and $30^{\circ}$ are produced. The ratio of the number of turns in $A$ and $B$ is

The scale of a galvanometer is divided into $25$ equal divisions. The resistance of the galvanometer is $100 \,\Omega$. The current sensitivity of the galvanometer is $4 \times 10^{-4} \,A/div$. What resistance in $ohm$ must be connected in series to measure $2.5 \,V$?

In an ammeter, $0.2\%$ of the main current passes through the galvanometer. If the resistance of the galvanometer is $G$, the resistance of the ammeter will be