Question 550: Current Electricity

Question

A balanced bridge is shown in the circuit diagram. The metre bridge wire has resistance $$1 \Omega \mathrm{m}^{-1}$$. The current drawn from the battery is (Internal resistance of battery is negligible)

Accepted Answer

Wire has a resitance $$1 \Omega \mathrm{cm}^{-1}$$.
$$	herefore$$ Resistance of $$40 \mathrm{~cm}$$ of wire $$=40 \Omega$$ and resistance of $$60 \mathrm{~cm}$$ of wire $$=60 \Omega$$
No current flows through the galvanometer since the bridge in balanced. Hence the branch containing the galvanometer can be removed.
For balanced bridge $$\frac{4}{40}=\frac{Y}{60}$$
$$	herefore Y=\frac{4 	imes 60}{40}=6 \Omega$$
$$4 \Omega$$ and $$6 \Omega$$ are in series. Their equivalent resistance is $$10 \Omega$$.
$$40 \Omega$$ and $$60 \Omega$$ are in series. Their equivalent resistance is $$100 \Omega$$.
$$10 \Omega$$ and $$100 \Omega$$ are in parallel
Their equivalent resistance is $$\frac{1000}{110} \Omega$$.
$$	herefore$$ The current $$\mathrm{I}=\frac{\mathrm{V}}{\mathrm{R}}=\frac{6 	imes 110}{1000}=0.66 \mathrm{~A}$$

Answer

0.44 A

Answer

0.66 A

Answer

0.88 A

Answer

0.22 A

Current Electricity

A balanced bridge is shown in the circuit diagram. The metre bridge wire has resistance $1 \Omega \mathrm{m}^{-1}$. The current drawn from the battery is (Internal resistance of battery is negligible)

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