Question

The range of an ammeter of resistance $'G'$ can be increased from $'I'$ to $'nI'$ by connecting

• A. a series resistance of $\frac{G}{n+1}\, \Omega $
• B. a shunt of $\frac{G}{n-1}\, \Omega $
• C. a shunt of $\frac{G}{n+1}\, \Omega $
• D. a series resistance of $\frac{G}{n-1}\, \Omega $

Answer 1

Answer: (B)

The range of an ammeter can be increased by connecting a shunt or parallel resistance to it, whose value is given by
$R=\left(\frac{I_{g}}{I-I_{g}}\right) G \Omega$
To increase the range from $I$ to $n I,$ the current passing through it is $I=n I_{g}$
Using this value in Eq. (i), we get
$ R =\left(\frac{I_{g}}{n I_{g}-I_{g}}\right) G $
$=\frac{G}{(n-1)} \Omega$