Question

A resistance of a galvanometer $G=6\, \Omega$ maximum current of $2\, amp$ is measured by it. Then required resistance to convert it into an ammeter reading up to $6\, A$, will be :

• A. $5\,\Omega $
• B. $ 4\,\Omega $
• C. $ 3\,\Omega $
• D. $ 2\,\Omega $

Answer 1

Answer: (C)

Here: Resistance of galvanometer
$G=6 \Omega$
Maximum current through the galvanometer $i_{g}=2A$
Current in ammeter $i=6A$
The current through galvanometer is given by
$i_{g}=\frac{S}{S +g}i$
or $2=\frac{S}{S+6}\times 6$
or $ 25+12=69$
So, $S=3\,\Omega $