Topic: Kirchhoff's laws and applications· Current Electricity

A constant voltage of 50 V is maintained between the points A and B of the circuit shown in the figure. The current through the branch CD of the circuit is :

bridge circuit: 1 ohm and 2 ohm top (A-C-B), 3 ohm and 4 ohm bottom, wire CD between middle junctions, 50 V battery across A,B

1. 1.5 A

2. 2.0 A

3. 2.5 A

4. 3.0 A

Doubtly Asked 30 Oct 2026 NEET UG 2025 Practice test neet Save WhatsApp Report

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Answer: 2. 2.0 A

Key idea: C and D are joined by a wire, so they are at the same potential. The circuit becomes two parallel pairs in series.

Left pair: $1\parallel3=\tfrac34\ \Omega$. Right pair: $2\parallel4=\tfrac43\ \Omega$. Total $=\tfrac34+\tfrac43=\tfrac{25}{12}\ \Omega$, so

$$I=\frac{50}{25/12}=24\ \mathrm A$$

Voltage across the left pair $=24\times\tfrac34=18$ V, across the right pair $=24\times\tfrac43=32$ V. Currents: $1\ \Omega$: 18 A; $3\ \Omega$: 6 A; $2\ \Omega$: 16 A; $4\ \Omega$: 8 A.

At junction C: 18 A arrives, 16 A leaves through $2\ \Omega$, so the wire CD carries $18-16=2$ A.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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A constant voltage of 50 V is maintained between the points A and B of the circuit shown in the figure. The current through the branch CD of the circuit is :

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