Physics - Current Electricity Question with Solution | TestHub

Initial range of the ammeter = $I$

Resistance of the ammeter = $R$

The range is increased by $nI$, so the new range of the ammeter is $I^{\prime }=I+nI$.

The maximum current that can flow through the ammeter is $I$. The remaining current must flow through the shunt resistance $S$ connected in parallel.

Current through the shunt, $I_S=I^{\prime }-I=(I+nI)-I=nI$

Since the ammeter and the shunt are in parallel, the potential difference across them is equal.

$I\times R=I_S\times S$

$I\times R=nI\times S$

$S=\frac{R}{n}$

Answer: $\frac{R}{n}$