Which of the following does not depend upon the magnetic effect of current?

The scale of a galvanometer is divided into $100$ equal divisions. It has a current sensitivity of $10 \text{ div./mA}$ and a voltage sensitivity of $4 \text{ div./mV}$. The resistance of the galvanometer is: (in $Omega$)

$A$ voltmeter with internal resistance of $x\text{ }\Omega$ can be used to measure up to $20\text{ V}$. In order to increase its measuring range to $30\text{ V}$,the required modification is to . . . . . . .

$A$ galvanometer has a resistance $100 \ \Omega$ and its full-scale deflection current is $10 \ mA$. What is the value of the shunt resistance required so that it can measure current up to $10 \ A$?

Why is the total resistance of a voltmeter kept very high?

The percentage error in the reading of the voltmeter in the figure shown here is nearly ............ $\%$