# Network Theory Questions and Answers – Kirchhoff’s Current Law

This set of Network Theory Multiple Choice Questions & Answers (MCQs) focuses on “Kirchhoff’s Current Law”.

1. Kirchhoff’s Current law is based on the law of conservation of ___________
a) energy
b) momentum
c) mass
d) charge

Explanation: Kirchhoff’s current law is based on the law of conservation of charge i.e, charge that flows in = charge that flows out.

2. The current law represents a mathematical statement of fact that ___________
a) voltage cannot accumulate at node
b) charge cannot accumulate at node
c) charge at the node is infinite
d) none of the mentioned

Explanation: Charge cannot accumulate at the node, it can only flow in and out of the node.

3. Kirchhoff’s current law is applied at ___________
a) loops
b) nodes
c) both loop and node
d) none of the mentioned

Explanation: Kirchhoff’s current law can be applicable to nodes only.

4. Determine the current in all resistors in the circuit shown below.

a) 2A, 4A, 11A
b) 5A, 4.8A, 9.6A
c) 9.3A, 20.22A, 11A
d) 10.56A, 24.65A, 14.79A

Explanation: All the resistors are in parallel, so the voltage across each resistor is the same V.
i1=V/7, i2 = V/3, i3=V/5. By current law, 50A = V/7 + V/3 + V/5. On solving, we obtain V and then values of i1, i2, i3.

5. For the circuit below , find the voltage across 5Ω resistor and the current through it.

a) 1.93 V
b) 2.83 V
c) 3.5 V
d) 5.7 V

Explanation: Here all the resistors are connected in parallel and let the voltage be V. Hence, i15=V/15, i5=V/5, i2=V/2, i1=V/1. By kirchhoff’s current law, V/15 + V/5 + V/2 V/1 +5 = 10. On solving equation, we obtain the value of V. As all resistors are in parallel, voltage across each is same as V.
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6. Determine the current through the resistor R3 shown in the figure using KCL.

a) 25mA
b) 10mA
c) 20mA
d) 35mA

Explanation: Using KCL, 60mA = 10mA + 25mA + i3.

7. Find the current i3 in the circuit shown below.

a) 2A
b) 1A
c) 3A
d) 0.5A

Explanation: By applying the KCL at the node in the circuit , 5A = 2A +i3.

8. Kirchhof’s current law can be mathematically stated as ___________
a) ∑k=0n I = 0
b) i2k=0n I = 0
c) i∑k=0n I = 0
d) none of the mentioned

Explanation: KCL states that the sum of currents entering and leaving a node is equal to zero.

9. Determine the current if a 20 coulomb charge passes a point in 0.25 seconds.
a) 10 A
b) 20 A
c) 2 A
d) 80 A

Explanation: By the definition of electric current, I=q/t.

10. Find the current through the branch containing resistance R3.

a) 2A
b) 3.25A
c) 2A
d) 2.75A

Explanation: By KCL, 5A = 0.25A + 2A + i3.

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