2026 Current ElectricitySymmetric resistor networks (Wheatstone-bridge-like circuits) Medium Question 1 of 130 in Current Electricity

A uniform metallic wire having resistance $4\ \Omega$ is bent to form a square loop (ABCD) (see figure). A resistance of $2\ \Omega$ is connected between points B and D and a battery of 2 V is connected across points A and C as shown in the figure. Now the value of current (I) is:

A 2 A
B 4 A
C 8 A
D 4.5 A

The answer is A.

Solution

Resistance of each side of the square $= \frac{4}{4} = 1\ \Omega$ With the battery across A and C, the circuit is a balanced Wheatstone bridge, so no current flows through the $2\ \Omega$ resistor between B and D. The two paths (A-B-C and A-D-C) are each $2\ \Omega$ in parallel, so $R_{net} = 1\ \Omega$ $I = \frac{E}{R_{net}} = \frac{2}{1} = 2$ A

Current Electricity in past papers

130 questions from this chapter have appeared across 27 exam years.