Question

The resistance of an ammeter which can measure $1A$ is $0.018\Omega$. It can be converted into an ammeter which can measure $10A$ by connecting ______.

• A. $0.18$ $\Omega$ in series
• B. $0.18$ $\Omega$ in parallel
• C. $0.002$ $\Omega$ in series
• D. $0.002$ $\Omega$ in parallel

Answer 1

The correct option is D $0.002$ $\Omega$ in parallel

Let $x$ $\Omega$ be connected in parallel then Req is the equivalent resistance
$\therefore \frac{0.018x}{x+0.018}=Req$

Equating potential difference across $R_{eq}$ and ammeter

$=10\left(\frac{0.018x}{x+0.018}\right)=1\left(0.018\right)$

$9x$$=$ $0.018$

$x$$=$$0.002$$\Omega$