## Kirchhoff’s Current Law MCQ (Interview-Exam) Question-Answer

**Q.1** Find the value of v if v1=20V and value of current source is 6A.

**A.** 12V

**B.** 16V

**C.** 10V

**D.** 14V

**Ans : **12V

**Explanation: ** The current through the 10 ohm resistor=v1/10=2A.Applying KCL at node 1: i5=i10+i2. i2=6-2=4A.

Thus the drop in the 2 ohm resistor = 4×2 = 8V.

v1=20V; hence v2=20-v across 2 ohm resistor=20-8=12V

v2=v since they are connected in parallel.

v=12V.

**Q.2** Calculate the current A.

**A.** 10A

**B.** 20A

**C.** 5A

**D.** 15A

**Ans : **15A

**Explanation: ** KCl states that the total current leaving the junction is equal to the current entering it. In this case, the current entering the junction is 5A+10A=15A.

**Q.3** Calculate the value of I3, if I1= 2A and I2=3A.

**A.** 5A

**B.** -1A

**C.** -5A

**D.** 1A

**Ans : **-5A

**Explanation: ** KCl, I1+I2+I3=0. Hence I3=-(I1+I2)=-5A.

**Q.4** Calculate the current across the 20 ohm resistor.

**A.** 1A

**B.** 0.33A

**C.** 0.67A

**D.** 20A

**Ans : **sadasA

**Explanation: ** V/10 +V/20 =1. V=20/3V So current through 20 ohm = V/20 = (20/3)/20 =1/3=0.33V.

**Q.5** What is the value of current if a 50C charge flows in a conductor over a period of 5 seconds?

**A.** 10A

**B.** 20A

**C.** 5A

**D.** 15A

**Ans : **10A

**Explanation: ** Current=Charge/Time. Here charge = 50c and time = 5seconds, so current = 50/5 = 10A.

**Q.6** Find the value of i2, i4 and i5 if i1=3A, i3=1A and i6=1A.

**A.** 4,-2,4

**B.** 4,2,4

**C.** 2,-1,2

**D.** 2,1,2

**Ans : **2,-1,2

**Explanation: ** At junction a: i1-i3-i2=0. i2=2A.

At junction b: i4+i2-i6=0. i4=-1A.

At junction c: i3-i5-i4=0. i5=2A.

**Q.7** KCL is applied at _________.

**A.** Node

**B.** Neither loop nor node

**C.** Loop

**D.** Both loop and node

**Ans : **Node

**Q.8** KCL deals with the conservation of?

**A.** Mass

**B.** Charge

**C.** Momentum

**D.** Potential Energy

**Ans : **Charge

**Q.9** What is the value of the current I?

**A.** 7A

**B.** 6A

**C.** 8A

**D.** 5A

**Ans : **8A

**Explanation: ** At the junction, I-2+3-4-5=0. Hence I=8A.

**Q.10** KCL can be applied for __________.

**A.** Non-planar networks

**B.** Neither planar nor non-planar

**C.** Planar networks

**D.** Both planar and non-planar

**Ans : **Both planar and non-planar

## Kirchhoff’s Current Law

**1. Conservation of Charge:** Kirchhoff’s Current Law is based on the principle of the conservation of electric charge. In any closed electrical circuit, the total electric current entering a junction is equal to the total current leaving the junction.

**2. Current at Junctions:** At any node or junction in an electrical circuit, the algebraic sum of currents entering the junction is equal to the algebraic sum of currents leaving the junction. Mathematically, ∑I_{in} = ∑I_{out}.

**3. Algebraic Sign Convention:** Kirchhoff’s Current Law uses an algebraic sign convention to determine the direction of currents. Currents entering a junction are considered positive, while currents leaving the junction are considered negative.

**4. Application to Series Circuits:** In a series circuit, where components are connected end-to-end, the current remains constant throughout the circuit. KCL simplifies to stating that the current entering one end of the series circuit is equal to the current leaving the other end.

**5. Application to Parallel Circuits:** In a parallel circuit, where components share common nodes but have different paths, KCL is applied at each junction. The sum of currents entering a node is equal to the sum of currents leaving the node.

**6. Loop and Mesh Analysis:** KCL is essential for techniques like loop analysis and mesh analysis, which are used to analyze complex electrical circuits. These methods rely on applying KCL at various nodes to derive equations for solving circuit parameters.

**7. Verification of Circuit Laws:** Kirchhoff’s Current Law, along with Kirchhoff’s Voltage Law (KVL), provides a way to check the accuracy of circuit analysis. If these laws are satisfied, it indicates that the analysis is correct and consistent with the principles of electrical circuits.

**8. Use in Electronic Devices:** Kirchhoff’s Current Law is a fundamental tool in the design and analysis of electronic circuits, helping engineers understand and predict the behavior of currents in complex systems.