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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