Current Electricity Question 13
Question 13 - 2024 (29 Jan Shift 1)
A galvanometer having coil resistance $10 \Omega$ shows a full scale deflection for a current of $3 \mathrm{~mA}$. For it to measure a current of $8 \mathrm{~A}$, the value of the shunt should be:
(1) $3 \times 10^{-3} \Omega$
(2) $4.85 \times 10^{-3} \Omega$
(3) $3.75 \times 10^{-3} \Omega$
(4) $2.75 \times 10^{-3} \Omega$
Show Answer
Answer: (3)
Solution:
Given $\mathrm{G}=10 \Omega$
$\mathrm{I}_{\mathrm{g}}=3 \mathrm{~mA}$
$\mathrm{I}=8 \mathrm{~A}$
In case of conversion of galvanometer into ammeter.
We have $\mathrm{I}{\mathrm{g}} \mathrm{G}=\left(\mathrm{I}-\mathrm{I}{\mathrm{g}}\right) \mathrm{S}$
$S=\frac{I_{g} G}{I-I_{g}}$
$S=\frac{\left(3 \times 10^{-3}\right) 10}{8-0.003}=3.75 \times 10^{-3} \Omega$
