Question

A galvanometer has a current range of 0 to 1 mA and voltage range 50 mV. The shunt required to convert this into an ammeter range 0.1A is

• A. $\frac{50}{99}\Omega$
• B. $\frac{42}{182}\Omega$
• C. $\frac{50}{989}\Omega$
• D. $\frac{50}{229}\Omega$

Answer 1

The correct option is A $\frac{50}{99}\Omega$

$V=i_{g}G$ (using the standard result)

$50\times {10}^{-3}=1\times {10}^{-3}G$

$G=50\Omega$

$S=\frac{i_{g}G}{i-i_g}$

$S=\frac{{10}^{-3}\times 50}{{10}^{-1}-{10}^{-3}}$

=$\frac{0.05}{0.099}$

=$\frac{50}{99}\Omega$