A voltmeter with internal resistance of \( x \, \Omega \) can be used to measure upto \( 20 \, \text{V} \). In order to increase its measuring range to \( 30 \, \text{V} \), the required modification is to ________.
Connect resistor of \( \frac{x}{2} \, \Omega \), in series with voltmeter
Connect resistor of \( \frac{x}{2} \, \Omega \), in parallel to voltmeter
Connect resistor of \( x \, \Omega \) in series with voltmeter
Connect resistor of \( 2x \, \Omega \) in parallel with voltmeter