
6 Analog Electronics
0(i)
(a)
(b)
V =2-
1 Ω
2 V
/ =
Load
ov
(c)
3 ?>A
I
/?L (ohms)
2 V (volts)
(d)
Figure i .4 The maximum power theorem.
(a) Ideal voltage source.
(b) Generator or source with internal resistance
R^.
(c) Connected to a load Ri.
(d) Ε = 1 V,
R s
= 1 Ω. Maximum power in the load occurs when
RL
=
Rs
and V = E/2 (the matched condition), but only
falls by 25% for
Ri .
= SR, and
Ri .
= RJ3. For the matched case the total power supplied by the battery is twice the power
supplied to the load. On short-circuit, four times the matched load power
is
supplied, all dissipated internally in the battery.
can be seen that the maximum power