Question

A galvanometer of resistance $G$ is converted into a voltmeter of range $0-1 V$ by connecting a resistance $R _{1}$ in series with it. The additional resistance that should be connected in series with $R _{1}$ to increase the range of the voltmeter to $-2 V$ will be :

• A. $R _{1}$
• B. $R _{1}+ G$
• C. $R _{1}- G$
• D. $G$

Answer 1

Answer: (B)

$R _{1}+ G$

Answer 2

$\Rightarrow 2= i _{ g }\left( R _{1}+ R _{2}+ G \right) \ldots(2)$
(1) $\% (2)$
$\Rightarrow \frac{1}{2}=\frac{G+R_{1}}{G+R_{1}+R_{2}}$
$G + R _{1}+ R _{2}=2 G +2 h _{1}$
$\left(R_{2}=G+R_{1}\right)$