$A$ galvanometer has a resistance of $50 \ \Omega$ and it allows a maximum current of $5 \ mA$. It can be converted into a voltmeter to measure up to $100 \ V$ by connecting in series a resistor of resistance: (in $\Omega$)

In a moving coil galvanometer,to make the field radial,what is done?

The coil in a moving coil galvanometer experiences a torque proportional to the current passed through it. If a steady current $i$ is passed through it,the deflection of the coil is found to be $90^o$. Now,the steady current is switched off and a charge $Q$ is suddenly passed through the coil. If the coil has $N$ turns of area $A$ each and its moment of inertia is $I$ about the axis it is going to rotate,then the maximum angle through which it deflects upon passing $Q$ is:

$A$ microammeter has a resistance of $100\,\Omega$ and a full-scale range of $50\,\mu A$. It can be used as a voltmeter or as a higher-range ammeter provided a resistance is added to it. Pick the correct range and resistance combination.

How are a voltmeter and an ammeter connected in a circuit? Explain.

For a moving coil galvanometer,the deflection in the coil is $0.05\,rad$ when a current of $10\,mA$ is passed through it. If the torsional constant of the suspension wire is $4.0 \times 10^{-5}\,Nm\,rad^{-1}$,the magnetic field is $0.01\,T$,and the number of turns in the coil is $200$,the area of each turn (in $cm^2$) is: