Question

The range of an ammeter of resistance ${}^{\prime }{G}^{\prime }$ can be increased from ${}^{\prime }{I}^{\prime }$ to ${}^{\prime }n{I}^{\prime }$ 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 $nI,$ the current passing through it is $I=n{I}_g$
Using this value in Eq. (i), we get
$R=\left(\frac{I_g}{n{I}_g-I_g}\right)G$
$=\frac{G}{(n-1)}\Omega$