51 ch26 dc circuits
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7/17/2019 51 Ch26 DC Circuits
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• Series and parallel resistors• Kirchhoff’s Rules for network problems
• Electrical meters and household circuits
• R-C circuits
DC CIRCUITS: Chapter 26
C 2012 ! "ecker
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#earnin$ %oals - we will learn&•
'ow to simplif( resistors connectedin a circuit in series and in parallel! • 'ow to simplif( and anal()e more
complicated networks usin$Kirchhoff’s Rules! • R-C circuits
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Series connection
Parallel connection
Resistors connected in a circuit in series orparallel can be simplified usin$ the followin$&
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C 1**+ ,c-ermott. et al!. /rentice 'all
Calculate the total resistance of each bo if
each bulb has a resistance of 1000 hms Ω
3!
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,ethod of simplif(in$ the circuit in a3 belowto $et the e4ui5alent resistance!
6e can then calculate the power / 7 82 Rdissipated in each resistor!
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Eercise 29!1:& ;our e4ui5alent li$ht bulbsR1 7 R2 7 R3 7 R4 7 <!=0 Ω. emf 7 *!00 >olts!
;ind current and power in each li$ht bulb!6hich bulb is bri$htest?
#ater. if bulb @< is remo5ed which bulbs
$et bri$hter? immer?
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n the course website. see old Aest @1from pre5ious semesters
for t(pical C circuit problems
B other t(pical problems on testsD
See
www!ph(sics!ssu!eduF"eckerFph(sics=1
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Ahese comple circuits cannotbe reduced to series G
parallel combinations!
So use Kirchhoff’s Rules&
Σ I j = 0 unction rule5alid at any unction3Hconser5ation of char$e
2 Σ ∆! j " = 0 loop rule5alid for any closed loop3Hconser5ation of ener$(
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Bt node B. Σ 8in 7 Σ 8out
81 I 83 7 82
Σ !rises = Σ !drops#oop @1&
82R2 Iε4I 81R1 7 ε1 I ε2
#oop @2&
ε3 I ε2 7 82R2 I 83R3
• #abel&: 8’sH
IF- on R’sHloops!
• 6rite e4uations!
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Figure 26.66
5.00 A = 8
4.0
0
"
83
82
#abel the : branch currents 82. 83. and 84!
Since >#$ across all : branches is the same and
is known& >4 7 84R4 7 =B <Ω3 7 20 >olts.
the currents and ε can be readil( sol5ed!
B
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>4 7 84R4 7 =B <Ω3 7 20 >olts
83 7 >3 F R3 7 <> F :Ω
7 1!:: B
Bt unction ". Σ 8 in 7 Σ 8 out
84 7 82 I 83 H 82 7 84 G 83 7 =B - 1!:B
82 7 :!JB
#oop @1& Σ > rises 7 Σ > dropsε 7 82R2 I 84R4 7 :!JB 2Ω3 I =B<Ω3
ε 7 2J!< >
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>4 7 84R4 7 =B <Ω3 7 20 >olts
83 7 >3 F R3 7 <> F :Ω 7 1!:: B
Bt unction ". Σ 8 in 7 Σ 8 out84 7 82 I 83 H 82 7 84 - 83 7 =B - 1!:B 7 :!JB
#oop @1&Σ
> rises 7Σ
> drops
7 I 7 I 7
5.0 A
4.0
0
B
83
82
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Figure 26.11
A(po on top of pa$e +*0 12th Edition3. 2nd line from top of pa$e&
ri$ht sideL should read bottomLSee ;i$ure 29!11 which is rotated *0o
from fi$ure in the 11th Edition!3
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E#ECAR8CB# ,EBSMR8% 8SARM,EAS G,EAERS
B d’Brson5al $al5anometer meter mo5ement
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B,,EAERS ha5e a 5er( small shunt resistor in themto reduce the effect of introducin$ the meterresistance into the circuit bein$ measured!
>#A,EAERS ∆>3 ha5e a 5er( lar%e series resistorin them to reduce the amount of current drawn fromthe circuit bein$ measured!
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•8SC'BR%8%& C'BR%8%&
•Bn RC circuitthat can be usedto char%e an&&ischar%e a
capacitorthrou$h aresistor3!
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•C'BR%8% B CB/BC8AR&
current 5s time
•C'BR%8% B CB/BC8AR&char$e 5s time
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•8SC'BR%8% B CB/BC8AR¤t 5s time
•8SC'BR%8% B CB/BC8AR&
char$e 5s time
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o
o
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•A battery, a capacitor, and a resistor are connected in series.
Which of the following affect(s) the maximum charge stored
on the capacitor?
•Q26.26
•A. the emf ε of the battery
•B. the capacitance C of the capacitor
•C. the resistance R of the resistor
•D. both ε and C
•E. all three of ε , C , and R
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'ouse wirin$ circuits
' d d ill i i i h d i f
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'and drill circuit with $round wire forsafet(
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C 2012 ; "ecker