Kirchhoff's Junction Rule

Question

At a junction in a network, currents of 5 A and 3 A enter while currents of 4 A and I leave through separate branches, so what is I?

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Kirchhoff's junction rule, a consequence of charge conservation, requires that the total current flowing into a node equals the total current flowing out, as formalised in NCERT Class 12, Chapter 3 (Current Electricity). No charge can accumulate at a point, so summing the entering currents gives $5 + 3 = 8$ A, and the leaving currents must also total 8 A. Since one exit branch carries 4 A, the remaining branch carries $I = 8 - 4 = 4$ A. The option 12 A wrongly adds all listed currents together without balancing directions. The option 2 A incorrectly subtracts the 3 A input from a partial sum. The option 8 A forgets that 4 A already leaves and assumes the whole incoming current exits through one branch. A consistency check confirms the balance: inflow $5 + 3 = 8$ A equals outflow $4 + 4 = 8$ A, so charge is conserved at the junction and the sign and magnitude are both physically sound.

Kirchhoff's Junction Rule

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