Question

An ammeter has a resistance of $G$ ohms and range of $I$ amperes. The value of resistance required in parallel to convert it into an ammeter of range $nI$ is

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

Answer 1

The correct option is C $G/(n-1)$

Ammeter has resistance $G$ ohm and let $S$ ohm be required shunt resistance connected in parallel to convert it into an ammeter of range nI.
As shown in the figure, by parallel combination:

$S\times I(n-1)=I\times G$

$S=\frac{G}{n-1}$