Question

A voltmeter has a resistance of $G$ ohms and range $V$ volts. The value of resistance required in series to convert it into voltmeter of range $nV$ is

• A. $nG$
• B. $G/n$
• C. $G/(n-1)$
• D. $(n-1)G$

Answer 1

Answer: (D)

$(n-1)G$

Voltmeter resistance G ohm and voltage V.
Initially, $V=$ $I_g$$G$
$I_g=\frac{V}{G}$
Let $R$ be the required resistance in series to convert it into voltmeter of range $V_1$$=nV$
Required resistance can be found from:
$V_1=I_g(G+R)$
$nV=\frac{V}{G}(G+R)$
$G+R=nG$
$\therefore$ $R=(n-1)G$