Two galvanometers $A$ and $B$ require $3\,mA$ and $5\,mA$ respectively to produce the same deflection of $10$ divisions. Then:

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 $\Omega$)

Certain galvanometers have a fixed core made of non-magnetic metallic material. The function of this metallic material is

$A$ galvanometer having a coil of resistance $30 \ \Omega$ needs $20 \ \text{mA}$ of current for full-scale deflection. If a maximum current of $3 \ \text{A}$ is to be measured using this galvanometer,the resistance of the shunt to be added to the galvanometer should be $\frac{30}{X} \ \Omega$,where $X$ is

The resistance of an ideal voltmeter is . . . . . . .

$A$ moving coil galvanometer has a coil with $175$ turns and an area of $1 \, cm^2$. It uses a torsion band with a torsion constant of $10^{-6} \, N \cdot m/rad$. The coil is placed in a magnetic field $B$ parallel to its plane. The coil deflects by $10^{\circ}$ for a current of $1 \, mA$. The value of $B$ (in Tesla) is approximately: