December 28, 2025
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.
