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Equation 1.4 shows that the pow€r associated with a basic ckcuit element
is simply the pmduct of the current in the element and the voltage adoss
the element. Therefore, power is a quaDtity associated with a pair of tei_
minals, and we have to be able to tell from our calculation whether power
is being delivered to the pair of teminals or extracted from it. This infor
mation comes ftom the corect application and interpretation of tle pas
sive sign convention.
If we use the passive sign convention, Eq. 1.4
is correct if the rcference
alirection for the current is in the direction of the rcference voltage drop
across
the terminals. Otherwise, Eq. 1.4 must be written with a minus sign.
In other words, if the current reference is il the direction of a refererce
voltage rise across
the teminals, the expression for the power is
(1.5)
1.6
Power
and Eneqy
'
I;:]
41._stl}l
,
l:l
.
L
I
*113
1
*f:]
(c)p=d
(d)p
=
,i
+
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This note was uploaded on 07/05/2010 for the course EE 100 taught by Professor Boser during the Spring '07 term at Berkeley.
 Spring '07
 Boser

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