Kirchhoff’s Current Law (KCL)

Kirchhoff’s Current Law (KCL)

Kirchhoff’s Current Law (KCL): At any instant the sum of all currents entering a node must be equal to all currents leaving the same node.

Mathematically KCL can be expressed as

·         KCL is the simply conservation of charge.

·         A node can’t accumulate or eliminate Charge.

Applying KCL:

To apply KCL successfully, we must first label all branch currents of interest and indicate their reference directions by means of arrows.

For Example:

·         If a current is unknown assume its direction.

·         Solve equations to find value of current.

·         Positive sign shows that the assumed direction is same. Negative sign shows that the assumed direction is false.

Solved Problem:

If i₅  =3A, i₆ =4A, Find i₃  so That i₂ = 1A

At Node C

i₄ = i₅ + i₆

i₄ = 3A+4A

i₄ = 7A

At Node B

i₂ = i₃ + i₄

i₃ = i₂ – i₄

i₃ = 1A – 7A

i₃ = -6A

Negative sign shows that the assumed direction is false.