Question

An ammeter has resistance $R_{0}$ and range $i$ . What resistance should be connected in parallel with it to increase its range by $ni$ ?

• A. $R_{0}/\left(n - 1\right)$
• B. $R_{0}/\left(n + 1\right)$
• C. $R _{0} / n ⁡$
• D. None of these

Answer 1

Answer: (C)

Given, $i _{g ⁡} = i ⁡ , G ⁡ = R ⁡_{0}$ ;
$i_{1}=n i+i⁡=\left(n ⁡ + 1\right)i⁡$
$\therefore S =\frac{i ⁡_{g ⁡} G ⁡}{i_{1} ⁡ - i ⁡_{g ⁡}}=\frac{i ⁡ R ⁡_{0}}{\left(n ⁡ + 1\right) i ⁡ - i ⁡}=\frac{R ⁡_{0}}{n ⁡}$