Question

What is the value of shunt resistance required to convert a galvanometer of resistance $100$ $\Omega$ into an ammeter of range $1A$ ?
Given : Full scale deflection of the galvanometer is $5mA$

• A. $\frac{5}{9.95}\Omega$
• B. $\frac{9.95}{5}\Omega$
• C. $0.5\Omega$
• D. $0.05\Omega$

Answer 1

Answer: (A)

By conversion of galvanometer into ammeter
$S=\left(\frac{I_g}{I-I_g}\right)G$
($I_g=$ Current through galvanometer
S = Shunt resistance
G == Galvanometer resistance)
where $I_g=5\times 10^{-3}A$
$I=1A$
$G=100\Omega$
$S=\left(\frac{5\times 10^{-3}}{1-5\times 10^{-3}}\right)\times 100$
$=\frac{5\times 10^{-3}\times 100\times 10^3}{(1000-5)}$
$=\frac{500}{995}=\frac{5}{9.95}\Omega$