Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): At any junction of a circuit carrying steady currents, the total current flowing into the junction is equal to the total current flowing out of it.
Reason (R): When the currents are steady, charge does not accumulate at any junction of the circuit.
In the light of the above statements, choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Both (A) and (R) are true and (R) is the correct explanation of (A).
Assertion (A) At any junction of a circuit carrying steady currents, the total current flowing into the junction is equal to the total current flowing out of it. — True. This is Kirchhoff’s junction rule. It holds at every junction of the circuit, whatever the number of wires meeting there.
Reason (R) When the currents are steady, charge does not accumulate at any junction of the circuit. — True. In a steady state, the charge at every point of the circuit stays the same with time. So no charge can collect at a junction.
Why R explains A?
The current into a junction is the rate at which charge arrives there. The current out is the rate at which charge leaves.
Since no charge collects at the junction, these two rates must be equal. So the junction rule comes from the conservation of charge stated in (R).
NCERT (2026-27):
Kirchhoff’s Rules – “(a) Junction rule: At any junction, the sum of the currents entering the junction is equal to the sum of currents leaving the junction …”
Kirchhoff’s Rules – “The proof of this rule follows from the fact that when currents are steady, there is no accumulation of charges at any junction or at any point in a line. Thus, the total current flowing in, (which is the rate at which charge flows into the junction), must equal the total current flowing out.”