Question

A galvanometer whose resistance is $120 \, \Omega$ gives full scale deflection with a current of $0.05 \,A$ so that it can read a maximum current of $10 \,A$. A shunt resistance is added in parallel with it. The resistance of the ammeter so formed is

• A. $0.06 \,\Omega$
• B. $0.006 \, \Omega$
• C. $0.6 \,\Omega$
• D. $6 \, \Omega$

Answer 1

Answer: (C)

Resistance of shunted ammeter $=\frac{G S}{G+S}$
Also $\frac{i}{i_{g}}=1+\frac{G}{S} $
$\Rightarrow \frac{G S}{G+S}=\frac{i_{g} \cdot G}{i}$
$\Rightarrow \frac{G S}{G+S}=\frac{0.05 \times 120}{10}=0.6 \,\Omega$