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Unformatted text preview: 34. The voltage diﬀerence across R is VR = E R /(R + 2.00 Ω), where R = (5.00 ΩR)/(5.00 Ω + R). Thus,
ER
R + 2.00 Ω 2 = 2
VR
1
=
R
R = PR E2
(2.00 Ω)(5.00 Ω + R)
1+
R
(5.00 Ω)R = E
1 + 2.00 Ω/R 1
R
−2 ≡ 2 E2
f (R ) where we use the equivalence symbol ≡ to deﬁne the expression f (R). To maximize PR we need to
minimize the expression f (R). We set
df (R)
49
4.00 Ω2
+
=−
=0
2
dR
R
25
to obtain R = (4.00 Ω2 )(25)/49 = 1.43 Ω. ...
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This note was uploaded on 11/12/2011 for the course PHYS 2001 taught by Professor Sprunger during the Fall '08 term at LSU.
 Fall '08
 SPRUNGER
 Physics

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