Question 573: Current Electricity

Question

A galvanometer of resistance $$200 \Omega$$ is to be converted into an ammeter. The value of shunt resistance which allows $$3 \%$$ of the mains current through the galvanometer is equal to (nearly)

Accepted Answer

The value of the required shunt $$(\mathrm{S})$$ is calculated by using
$$\begin{aligned}
& \frac{I_{\mathrm{g}}}{\mathrm{I}}=\frac{\mathrm{S}}{\mathrm{S}+\mathrm{G}} \
& 	herefore \frac{3}{100}=\frac{\mathrm{S}}{\mathrm{S}+200} \
& 	herefore 100 \mathrm{~S}=3 \mathrm{~S}+600 \quad 	herefore 97 \mathrm{~S}=600 \
& 	herefore \mathrm{S}=\frac{600}{97} \doteqdot 6 \Omega
\end{aligned}$$
[Note for $$\mathrm{S}=6,97 \mathrm{~S}=582$$ and for $$\mathrm{S}=7,97 \mathrm{~S}=679$$ ]

Answer

$$6 \Omega$$

Answer

$$7 \Omega$$

Answer

$$10 \Omega$$

Answer

$$5 \Omega$$

Current Electricity

A galvanometer of resistance $200 \Omega is to be converted into an ammeter. The value of shunt resistance which allows 3 \%$ of the mains current through the galvanometer is equal to (nearly)

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