Question

A milliammeter of range 10 mA has a coil of resistance 1 $\Omega$. To use it as an ammeter of range 1A, the required shunt must have a resistance of

• A. $\frac{1}{101}\Omega$
• B. $\frac{1}{100}\Omega$
• C. $\frac{1}{99}\Omega$
• D. $\frac{1}{9}\Omega$

Answer 1

The correct option is C $\frac{1}{99}\Omega$

The required shunt, $S=\frac{i_g}{I-i_g}G=\frac{10\times {10}^{-3}}{1-(10\times {10}^{-3})}\times 1=\frac{0.01}{1-0.01}=\frac{1}{99}\Omega$