In the conversion of a moving coil galvanometer into an ammeter of a required range,what is the resistance of the ammeter so formed? [$S$ = shunt resistance and $G$ = resistance of the galvanometer]

$A$ $50\,\Omega$ resistance is connected to a battery of $5\,V$. $A$ galvanometer of resistance $100\,\Omega$ is to be used as an ammeter to measure current through the resistance. For this,a resistance $r_s$ is connected to the galvanometer. Which of the following connections should be employed if the measured current is within $1\%$ of the current without the ammeter in the circuit?

To convert a $800\, mV$ range millivoltmeter of resistance $40\,\Omega$ into an ammeter of $100\, mA$ range,the resistance to be connected as a shunt is .............. $\Omega$.

$A$ galvanometer with $50$ divisions on the scale has a resistance of $25 \Omega$. $A$ current of $2 \times 10^{-4} \text{ A}$ gives a deflection of one scale division. The additional series resistance required to convert it into a voltmeter reading up to $25 \text{ V}$ is $.... \Omega$.

When a resistance of $100 \Omega$ is connected in series with a galvanometer of resistance $G$,its range is $V$. To double its range,a resistance of $1000 \Omega$ is connected in series. The value of $G$ is: (in $\Omega$)

$A$ stray magnetic field does $\underline{\text{NOT}}$ affect the deflection of a moving coil galvanometer because