Question

The range of a voltmeter of resistance $300\Omega$ is $5V$. The resistance to be connected to convert it as an ammeter of range $5A$ is

• A. $1\Omega$ in series
• B. $1\Omega$ in parallel
• C. $0.1\Omega$ in series
• D. $0.1\Omega$ in parallel

Answer 1

The correct option is B $1\Omega$ in parallel

Let resistance to be connected in parallel be $x$
$R_{eq=}\frac{300x}{300+x}$
resistance is to be connected in parallel to make it an ammeter
$i_1=\frac{V}{R}=\frac{5}{300}$
$\frac{i_1}{i_2}=\frac{R_2}{R_1}=\frac{\left(\frac{5}{300}\right)}{5}=\frac{\left(\frac{300x}{300+x}\right)}{300}$
$300+x=300x$
= $x=\frac{300}{299}=1\Omega inparallel$