Page 155 - Basic Electrical Engineering

Approaching from B to A

V OC = 24 − 8 × 0.67 = 18.64 V

The same result will be arrived at when we approach from A to B.
Now we calculate R across terminals A and B by short circuiting the
eq
voltage sources or by replacing them by their internal resistances. Across
terminals AB we find two resistances of 8 Ω and 10 Ω connected in parallel.

R across terminals A and
eq

Thus, Thevenin’s equivalent circuit is represented as in Fig. 2.50

Figure 2.50

Current through R with its variable values i.e., for R = 2Ω and R = 5Ω are
calculated as

and

Now, we are in a position to state Thevenin’s Theorem as

Any two terminals of an electrical network consisting of active and passive
elements (i.e., voltage sources and resistors) can be replaced by an

equivalent voltage source and an equivalent series resistance. The voltage