Class notes circuit and network theory

EEE/ETI 1202
CIRCUITS & NETWORK THEORY I

LECTURE 4

, LECTURE ROADMAP

• Circuit Analysis-Theorems
– Thevenin’s Theorem

– Norton’s Theorem

– Maximum Power Theorem

– Examples

, Thevenin’s Theorem
• Thevenin’s theorem as applied to d.c. circuits is stated below :
• Any linear, bilateral network having terminals A and B can be replaced by
single source of e.m.f. VTh in series with a single resistance RTh.
• (i) The e.m.f. VTh is the voltage obtained across terminals A and B with load
if any removed i.e. it is open-circuited voltage between terminals A and B.
• (ii) The resistance RTh is the resistance of the network measured betwee
terminals A and B with load removed and sources of e.m.f. replaced by the
internal resistances. Ideal voltage sources are replaced with short circuits an
ideal current sources are replaced with open circuits.

, Thevenin’s Theorem

• Consider the circuit shown in Fig. (i). As far as the circuit behind terminals AB
is concerned, it can be replaced by a single source of e.m.f. VTh in series with
single resistance RTh as shown in Fig. b (ii).