A moving coil instrument having a resistance of $10 \: \Omega$, gives a full-scale deflection when the current is $10$ mA. What should be the value of the series resistance, so that it can be used as a voltmeter for measuring potential difference up to $100$ V?
1. $9 \: \Omega$
2. $99 \: \Omega$
3. $990 \: \Omega$
4. $9990 \: \Omega$