sufficient, powerful set of tools for analysing a large variety of electric
circuits
•
These laws are formally known as
Kirchhoff’s current law (KCL)
and
Kirchhoff’s voltage law (KVL)
Kirchhoff’s Laws
 Kirchhoff’s first law is based on the
law of conservation of charge
 Meaning,
the algebraic sum of charges within a system cannot
change

Kirchhoff’s Current Law (KCL) states that the algebraic sum of
currents entering a node (or a closed boundary) is zero
Kirchhoff’s Laws
Where
is the number of branches connected to the node
and
is the nth current entering (or leaving) the node
Kirchhoff’s Laws
Kirchhoff’s Laws
 Kirchhoff’s second law is based on the principle of conservation of
energy

Kirchhoff’s Voltage Law (KVL) states that the algebraic sum of all
voltages around a closed path (or loop) is zero
Kirchhoff’s Laws
Expressed mathematically, KVL states that
Wherein
is the number of branches (or voltages) in the loop and
is the nth voltage
Kirchhoff’s Laws
 KVL can be applied in both clockwise and counter clockwise direction.
Either way, the sum of the voltages around the loop is equivalent to
zero
 For nonsource elements, voltage polarities should be assigned (if not
stated by the problem!)
 KVL can also be reinterpreted as
Kirchhoff’s Laws
 When voltage sources are connected in series, KVL can be applied to
obtain the total voltage
Example 6
For the circuit shown, find the voltages
and
Example 7
For the circuit shown, find the voltages
and
Example 8
For the circuit shown, find the voltages
and
You've reached the end of your free preview.
Want to read all 57 pages?
 Spring '20
 Thévenin's theorem, Voltage source, Current Source, Kirchhoff