()
2
avg
30.0V
90.0W.
2 5.00
P
==
Ω
(d) At maximum power, the reactances are equal:
X
L
= X
C
. The phase angle
φ
in this case
may be found from
tan
,
=
−
=
XX
R
LC
0
which implies
= 0
°
.
(e) At maximum power, the power factor is cos
= cos 0° = 1.
(f) The minimum average power is
P
avg
= 0 (as it would be for an open switch).
(g) On the other hand, at minimum power
X
C
∝
1/
C
is infinite, which leads us to set
tan
=−∞
. In this case, we conclude that
= –90°.
(h) At minimum power, the power factor is cos
= cos(–90°) = 0.
59. We shall use
22
avg
2
2
2
.
2
21
/
mm
dd
RR
P
Z
RLC
εε
ωω
⎡
⎤
+−
⎣
⎦
where
ZR
L
C
=+
−
2
2
1
/
b
g
is the impedance.
(a) Considered as a function of
C, P
avg
has its largest value when the factor
2
2
1/
R
has the smallest possible value. This occurs for
This is the end of the preview. Sign up
to
access the rest of the document.
 Spring '08
 Any
 Physics

Click to edit the document details