Connect the R
TH
in
series with Voltage Source V
TH
and re-connect the
load resistor across the
load terminals(A&B) as shown in fig (5) i.e. Thevenin circuit with load resistor. This is the
Thevenin’s equivalent circuit
R
TH
V
TH
Fig(5)
Now apply Ohm’s law and calculate the total load current from fig 5.
I
L
= V
TH
/ (R
TH
+ R
L
)= 12V / (11kΩ + 5kΩ) = 12/16kΩ
I
L
= 0.75mA
And V
L
= I
L
x R
L
= 0.75mA x 5kΩ
V
L
= 3.75V
Norton’s Theorem Statement :
Any linear, bilateral two terminal network
consisting of sources and
resistors(Impedance),can be replaced by an equivalent circuit consisting
of a current source in
parallel with a resistance (Impedance),the current source being the short circuited current across
the load terminals and the resistance being the internal resistance of the source network looking
through the open circuited load terminals.
(a)
(b)
Figure (a)
shows a simple block representation of a network with several active /
passive
elements with the load resistance
R
L
connected across the terminals
‘a
&
b’
and figure (b) shows
the
Norton equivalent circuit
with
I
N
connected across
R
N
&
R
L
.
Main steps to find out I
N
and R
N
:
1.
The terminals of the branch/element through which the current
is to be found out are
marked as say
a & b
after removing the concerned branch/element.
