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

$A$ galvanometer has resistance '$G$' and range '$V_g$'. How much resistance is required to read voltage up to '$V$' volt?

$A$ moving coil galvanometer is converted into an ammeter reading up to $0.03\,A$ by connecting a shunt of resistance $4r$ across it,and into an ammeter reading up to $0.06\,A$ when a shunt of resistance $r$ is connected across it. What is the maximum current which can be sent through this galvanometer if no shunt is used?

$A$ galvanometer of resistance $30 \Omega$ is connected to a battery of emf $2 \text{ V}$ with $1970 \Omega$ resistance in series. $A$ full-scale deflection of $20$ divisions is obtained in the galvanometer. To reduce the deflection to $10$ divisions,the total resistance in series required is: (in $\Omega$)

$A$ galvanometer of resistance $50 \Omega$ gives a full-scale deflection for a current of $5 \times 10^{-4} \text{ A}$. The resistance that should be connected in series with the galvanometer to read $3 \text{ V}$ is: (in $\Omega$)

$A$ galvanometer of resistance $G$ is shunted by a resistance of $5 \Omega$. To keep the main current in the circuit unchanged,the resistance to be put in series with the same galvanometer is