ECGR 2161- Basic Electrical Engineering I
Summer 2023
ECGR 2161- Basic Electrical Engineering I
Summer 2023
Kirchhoff’s Current Law (KCL)
The algebraic sum of all the currents entering any node in a
circuit equals zero.
Kirchhoff’s Voltage Law (KVL)
The algebraic sum of all the voltages around any closed loop in
a circuit equals zero.
Note – a node is a point where two or more circuit elements are
connected.
Note – a closed loop starts at any node, travels through selected circuit
elements, and returns back to the starting node without including any
intermediate nodes more than once.
ECGR 2161- Basic Electrical Engineering I
Summer 2023
ECGR 2161- Basic Electrical Engineering I
Summer 2023
ECGR 2161- Basic Electrical Engineering I
Summer 2023
ECGR 2161- Basic Electrical Engineering I
Summer 2023
Equivalent Circuits
Idea is to make circuits simpler
to solve.
ECGR 2161- Basic Electrical Engineering I
Summer 2023
Equivalent Circuits
Idea is to make circuits simpler
to solve.
ECGR 2161- Basic Electrical Engineering I
Summer 2023
ECGR 2161- Basic Electrical Engineering I
Summer 2023
Source transformation
Under what condition(s) are the two circuits below
“equivalent”?
When the same current is flowing thru RL, and therefore the
same voltage and power.
iL =
vS
R + RL
 = ൗ   = (|| ) 
R || RL
RRL R + RL
RiS
iS =
iS =
RL
RL
R + RL
 vS = RiS -- the condition for source transformation
iL =
ECGR 2161- Basic Electrical Engineering I
Summer 2023
ECGR 2161- Basic Electrical Engineering I
Summer 2023
Y-∆ Transformation
ECGR 2161- Basic Electrical Engineering I
Summer 2023
Y-∆ Transformation
ECGR 2161- Basic Electrical Engineering I
Summer 2023