Kirchhoffs Current Law

  • Explain how to apply Kirchhoff Current Law (KCL) to electric circuits.

  • Be able to write KCL at every node in the circuit.

  • Be able to solve the KCL equations, especially for simple circuits.

Kirchhoff's Current Law

The algebraic sum of the currents entering a node must equal the sum of the currents exiting a node.

If there is a junction where \(I_{_{1}} , I_{_{2}} , I_{_{3}}\) are the currents entering and \(I_{_{4}} , I_{_{5}}\) are currents leaving, then

\[I_{_{1}} + I_{_{2}} + I_{_{3}} - I_{_{4}} - I_{_{5}} = 0\]

Solved Examples

Solved Example:

19-1-01

Kirchhoff's current law states that:

Solution:
Kirchhoff's current law (1st Law) states that current flowing into a node (or a junction) must be equal to current flowing out of it. This is a consequence of charge conservation.

Correct Answer: B

Solved Example:

19-1-02

Kirchhoff's current law is applicable to only:

Solution:
Kirchhoff's Laws describe current in a node and voltage around a loop.

Correct Answer: A

Solved Example:

19-1-03

Two components are in series if they have: (DFCCIL Executive Electrical 2016)

Correct Answer: A

Solved Example:

19-1-04

When two components are in parallel, the circuit has:

Correct Answer: B

Solved Example:

19-1-05

As a general rule, how are electronic components connected when placed into circuit?

Correct Answer: C

Solved Example:

19-1-06

What determines whether connected resistors are in series, parallel, or series-parallel?

Correct Answer: A

Solved Example:

19-1-07

Where can the voltage divider formula be used in a series-parallel circuit?

Correct Answer: A

Solved Example:

19-1-08

Which of the following is the more useful in solving series-parallel circuit problems?

Correct Answer: C