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Electricity & MagnetismLecture 18
Today’sConcepts: A)Induc)on
B)RLCircuits
Electricity&Magne/smLecture18,Slide1
Wednesday, July 6, 16
ExtendeddeadlineoneforFlipItPhysicshomeworkduelastnight:! 80%extendedun)lJuly10.
Wednesday, July 6, 16
Stuff you said..
WilltherebemorelabacAviAesinvolvingoscilloscopes?UnlikelabacAviAesinvolvingmagnets,theoscilloscopesareforeign,new,andcuriouslyinteresAngtoplay/learnwithduetotheabove?
WhataretheexactdifferencesbetweentheCapacitorandInductor.InwhichsituaAonwouldIusetheCapacitorinsteadoftheInductororviceversa?
Wednesday, July 6, 16
Stuff you said..
WilltherebemorelabacAviAesinvolvingoscilloscopes?UnlikelabacAviAesinvolvingmagnets,theoscilloscopesareforeign,new,andcuriouslyinteresAngtoplay/learnwithduetotheabove?
WhataretheexactdifferencesbetweentheCapacitorandInductor.InwhichsituaAonwouldIusetheCapacitorinsteadoftheInductororviceversa?
http://www.sfu.ca/phys/141/1154/Schedule141.pdf
Wednesday, July 6, 16
Stuff you said..
WilltherebemorelabacAviAesinvolvingoscilloscopes?UnlikelabacAviAesinvolvingmagnets,theoscilloscopesareforeign,new,andcuriouslyinteresAngtoplay/learnwithduetotheabove?
WhataretheexactdifferencesbetweentheCapacitorandInductor.InwhichsituaAonwouldIusetheCapacitorinsteadoftheInductororviceversa?
http://www.sfu.ca/phys/141/1154/Schedule141.pdf
Wednesday, July 6, 16
Stuff you said..
WilltherebemorelabacAviAesinvolvingoscilloscopes?UnlikelabacAviAesinvolvingmagnets,theoscilloscopesareforeign,new,andcuriouslyinteresAngtoplay/learnwithduetotheabove?
WhataretheexactdifferencesbetweentheCapacitorandInductor.InwhichsituaAonwouldIusetheCapacitorinsteadoftheInductororviceversa?
http://www.sfu.ca/phys/141/1154/Schedule141.pdf
Capacitors are yin — Inductors are yang
Wednesday, July 6, 16
Wednesday, July 6, 16
Today’s Experiment
Electricity&Magne/smLecture18,Slide2
Loop area A
Wednesday, July 6, 16
Today’s Experiment
Electricity&Magne/smLecture18,Slide2
Loop area A
Wednesday, July 6, 16
Today’s Experiment
Electricity&Magne/smLecture18,Slide2
Loop area A
E = ��B
dt= �A
dBdt
Wednesday, July 6, 16
Today’s Experiment
Electricity&Magne/smLecture18,Slide2
Loop area A
E = ��B
dt= �A
dBdt
Wednesday, July 6, 16
E = ��B
dt= �NA
dBdt
Today’s Experiment
Electricity&Magne/smLecture18,Slide2
Loop area A
E = ��B
dt= �A
dBdt
Wednesday, July 6, 16
E = ��B
dt= �NA
dBdt
Today’s Experiment
Electricity&Magne/smLecture18,Slide2
Loop area A
E = ��B
dt= �A
dBdt
If there are more turns N in the loop,
Wednesday, July 6, 16
From the Prelecture: Self Inductance
Electricity&Magne/smLecture18,Slide2
Wednesday, July 6, 16
Wrapawireintoacoiltomakean“inductor”…
dIdt
ε = −L
From the Prelecture: Self Inductance
Electricity&Magne/smLecture18,Slide2
Wednesday, July 6, 16
currentI
L
What this really means:
Electricity&Magne/smLecture18,Slide3
Wednesday, July 6, 16
currentI
L
dIdt
εL = −L
What this really means:
Electricity&Magne/smLecture18,Slide3
Wednesday, July 6, 16
currentI
L
dIdt
εL = −L
emfinducedacrossLtriestokeepIconstant.
What this really means:
Electricity&Magne/smLecture18,Slide3
Wednesday, July 6, 16
currentI
L
dIdt
εL = −L
emfinducedacrossLtriestokeepIconstant.
Inductorspreventdiscon)nuouscurrentchanges!
What this really means:
Electricity&Magne/smLecture18,Slide3
Wednesday, July 6, 16
currentI
L
dIdt
εL = −L
emfinducedacrossLtriestokeepIconstant.
Inductorspreventdiscon)nuouscurrentchanges!
It’slikeiner)a!
What this really means:
Electricity&Magne/smLecture18,Slide3
Wednesday, July 6, 16
Twosolenoidsaremadewiththesamecrosssec/onalareaandtotalnumberofturns.InductorBistwiceaslongasinductorA
ComparetheinductanceofthetwosolenoidsA)LA = 4 LB B)LA = 2 LB C)LA = LB D)LA = (1/2) LB E)LA = (1/4) LB
CheckPoint 2
Electricity&Magne/smLecture18,Slide4
Wednesday, July 6, 16
Twosolenoidsaremadewiththesamecrosssec/onalareaandtotalnumberofturns.InductorBistwiceaslongasinductorA
ComparetheinductanceofthetwosolenoidsA)LA = 4 LB B)LA = 2 LB C)LA = LB D)LA = (1/2) LB E)LA = (1/4) LB
CheckPoint 2
Electricity&Magne/smLecture18,Slide4
Wednesday, July 6, 16
Twosolenoidsaremadewiththesamecrosssec/onalareaandtotalnumberofturns.InductorBistwiceaslongasinductorA
ComparetheinductanceofthetwosolenoidsA)LA = 4 LB B)LA = 2 LB C)LA = LB D)LA = (1/2) LB E)LA = (1/4) LB
(1/2)2 2
CheckPoint 2
Electricity&Magne/smLecture18,Slide4
Wednesday, July 6, 16
Twosolenoidsaremadewiththesamecrosssec/onalareaandtotalnumberofturns.InductorBistwiceaslongasinductorA
ComparetheinductanceofthetwosolenoidsA)LA = 4 LB B)LA = 2 LB C)LA = LB D)LA = (1/2) LB E)LA = (1/4) LB
(1/2)2 2
CheckPoint 2
Electricity&Magne/smLecture18,Slide4
Wednesday, July 6, 16
Twosolenoidsaremadewiththesamecrosssec/onalareaandtotalnumberofturns.InductorBistwiceaslongasinductorA
ComparetheinductanceofthetwosolenoidsA)LA = 4 LB B)LA = 2 LB C)LA = LB D)LA = (1/2) LB E)LA = (1/4) LB
(1/2)2 2
CheckPoint 2
Electricity&Magne/smLecture18,Slide4
Wednesday, July 6, 16
Twosolenoidsaremadewiththesamecrosssec/onalareaandtotalnumberofturns.InductorBistwiceaslongasinductorA
ComparetheinductanceofthetwosolenoidsA)LA = 4 LB B)LA = 2 LB C)LA = LB D)LA = (1/2) LB E)LA = (1/4) LB
(1/2)2 2
CheckPoint 2
Electricity&Magne/smLecture18,Slide4
Wednesday, July 6, 16
RL
VBATT
I = 0
Whennocurrentisflowingini)ally:
How to think about RL circuits Episode 1:
VL
Electricity&Magne/smLecture18,Slide5
Wednesday, July 6, 16
RL
VBATT
I = 0
Whennocurrentisflowingini)ally:
How to think about RL circuits Episode 1:
VL
Electricity&Magne/smLecture18,Slide5
Wednesday, July 6, 16
RL
At t = 0:I = 0VL = VBATTVR = 0(L islikeagiantresistor)
VBATT
I = 0
Whennocurrentisflowingini)ally:
How to think about RL circuits Episode 1:
VL
Electricity&Magne/smLecture18,Slide5
Wednesday, July 6, 16
RL
At t = 0:I = 0VL = VBATTVR = 0(L islikeagiantresistor)
VBATT
I = 0
At t >> L/R:VL = 0 VR = VBATTI = VBATT/R(Lislikeashortcircuit)
R
I = V/R
L
VBATT
Whennocurrentisflowingini)ally:
How to think about RL circuits Episode 1:
VL
Electricity&Magne/smLecture18,Slide5
Wednesday, July 6, 16
WhatisthecurrentIthroughthever/calresistorimmediatelyaRertheswitchisclosed?
(+isinthedirec/onofthearrow)
A)I = V/R B)I = V/2R C)I = 0 D)I = −V/2R E)I = −V/R
Inthecircuit,theswitchhasbeenopenforalong/me,andthecurrentiszeroeverywhere.
At/met=0theswitchisclosed.
CheckPoint 4
Electricity&Magne/smLecture18,Slide6
Wednesday, July 6, 16
WhatisthecurrentIthroughthever/calresistorimmediatelyaRertheswitchisclosed?
(+isinthedirec/onofthearrow)
A)I = V/R B)I = V/2R C)I = 0 D)I = −V/2R E)I = −V/R
Inthecircuit,theswitchhasbeenopenforalong/me,andthecurrentiszeroeverywhere.
At/met=0theswitchisclosed.
IL = 0
CheckPoint 4
Electricity&Magne/smLecture18,Slide6
Wednesday, July 6, 16
WhatisthecurrentIthroughthever/calresistorimmediatelyaRertheswitchisclosed?
(+isinthedirec/onofthearrow)
A)I = V/R B)I = V/2R C)I = 0 D)I = −V/2R E)I = −V/R
Inthecircuit,theswitchhasbeenopenforalong/me,andthecurrentiszeroeverywhere.
At/met=0theswitchisclosed.
IL = 0
CheckPoint 4
Electricity&Magne/smLecture18,Slide6
Wednesday, July 6, 16
WhatisthecurrentIthroughthever/calresistorimmediatelyaRertheswitchisclosed?
(+isinthedirec/onofthearrow)
A)I = V/R B)I = V/2R C)I = 0 D)I = −V/2R E)I = −V/R
Inthecircuit,theswitchhasbeenopenforalong/me,andthecurrentiszeroeverywhere.
At/met=0theswitchisclosed.
IL = 0
CheckPoint 4
Electricity&Magne/smLecture18,Slide6
Wednesday, July 6, 16
WhatisthecurrentIthroughthever/calresistorimmediatelyaRertheswitchisclosed?
(+isinthedirec/onofthearrow)
A)I = V/R B)I = V/2R C)I = 0 D)I = −V/2R E)I = −V/R
Inthecircuit,theswitchhasbeenopenforalong/me,andthecurrentiszeroeverywhere.
At/met=0theswitchisclosed.
IL = 0
CheckPoint 4
Electricity&Magne/smLecture18,Slide6
Wednesday, July 6, 16
WhatisthecurrentIthroughthever/calresistoraRertheswitchhasbeenclosedforalong/me?
(+isinthedirec/onofthearrow)
A)I=V/R B) I =V/2RC)I= 0D)I=−V/2R E)I= −V/R
RL Circuit (Long Time)
Electricity&Magne/smLecture18,Slide7
Wednesday, July 6, 16
WhatisthecurrentIthroughthever/calresistoraRertheswitchhasbeenclosedforalong/me?
(+isinthedirec/onofthearrow)
A)I=V/R B) I =V/2RC)I= 0D)I=−V/2R E)I= −V/R
RL Circuit (Long Time)
Electricity&Magne/smLecture18,Slide7
Wednesday, July 6, 16
WhatisthecurrentIthroughthever/calresistoraRertheswitchhasbeenclosedforalong/me?
(+isinthedirec/onofthearrow)
A)I=V/R B) I =V/2RC)I= 0D)I=−V/2R E)I= −V/R
RL Circuit (Long Time)
Electricity&Magne/smLecture18,Slide7
Wednesday, July 6, 16
RL
VBATT
I = V/R
R
When steady current is flowing initially:
How to Think about RL Circuits Episode 2:
VL
Electricity&Magne/smLecture18,Slide8
Wednesday, July 6, 16
RL
VBATT
I = V/R
R
I = VBATT/RVR = IR VL = VR
At t = 0:
When steady current is flowing initially:
How to Think about RL Circuits Episode 2:
VL
Electricity&Magne/smLecture18,Slide8
Wednesday, July 6, 16
RL
VBATT
I = V/R
At t >> L/R:I = 0VL = 0VR = 0
R
I = 0
LR
I = VBATT/RVR = IR VL = VR
At t = 0:
When steady current is flowing initially:
How to Think about RL Circuits Episode 2:
VL
Electricity&Magne/smLecture18,Slide8
Wednesday, July 6, 16
WhatisthecurrentIthroughthever/calresistorimmediatelyaRertheswitchisopened?
(+isinthedirec/onofthearrow)
A)I=V/RB)I=V/2RC)I=0 D)I= −V/2RE)I= −V/R
AReralong/me,theswitchisopened,abruptlydisconnec/ngthebaXeryfromthecircuit.
CheckPoint 6
Electricity&Magne/smLecture18,Slide9
Wednesday, July 6, 16
WhatisthecurrentIthroughthever/calresistorimmediatelyaRertheswitchisopened?
(+isinthedirec/onofthearrow)
A)I=V/RB)I=V/2RC)I=0 D)I= −V/2RE)I= −V/R
AReralong/me,theswitchisopened,abruptlydisconnec/ngthebaXeryfromthecircuit.
CheckPoint 6
Electricity&Magne/smLecture18,Slide9
Wednesday, July 6, 16
WhatisthecurrentIthroughthever/calresistorimmediatelyaRertheswitchisopened?
(+isinthedirec/onofthearrow)
A)I=V/RB)I=V/2RC)I=0 D)I= −V/2RE)I= −V/R
AReralong/me,theswitchisopened,abruptlydisconnec/ngthebaXeryfromthecircuit.
CheckPoint 6
Electricity&Magne/smLecture18,Slide9
Wednesday, July 6, 16
R
I
L
Why is there Exponential Behavior?
Electricity&Magne/smLecture18,Slide10
Wednesday, July 6, 16
R
I
L+
−
−
+
Why is there Exponential Behavior?
Electricity&Magne/smLecture18,Slide10
Wednesday, July 6, 16
R
I
V = IRL+
−
−
+
Why is there Exponential Behavior?
Electricity&Magne/smLecture18,Slide10
Wednesday, July 6, 16
R
I
V = IRdIdtV = L L
+
−
−
+
Why is there Exponential Behavior?
Electricity&Magne/smLecture18,Slide10
Wednesday, July 6, 16
R
I
V = IRdIdtV = L L
+
−
−
+
Why is there Exponential Behavior?
Electricity&Magne/smLecture18,Slide10
Wednesday, July 6, 16
R
I
V = IRdIdtV = L L
+
−
−
+
Why is there Exponential Behavior?
Electricity&Magne/smLecture18,Slide10
where
Wednesday, July 6, 16
R
I
V = IRdIdtV = L L
+
−
−
+
Why is there Exponential Behavior?
VL
Electricity&Magne/smLecture18,Slide10
where
Wednesday, July 6, 16
Prelecture:
RL
I
Lecture:
VLVBATT
Electricity&Magne/smLecture18,Slide11
Wednesday, July 6, 16
Prelecture:
RL
I
Lecture:
VLVBATT
Didwemessup?
Electricity&Magne/smLecture18,Slide11
Wednesday, July 6, 16
Prelecture:
RL
I
Lecture:
VLVBATT
Didwemessup?
No:Theresistanceissimplytwiceasbiginonecase.
Electricity&Magne/smLecture18,Slide11
Wednesday, July 6, 16
ARerlong/meat0,movedto1 ARerlong/meat0,movedto2
A(erswitchmoved,whichcasehaslarger6meconstant?
A)Case1B)Case2C)Thesame
CheckPoint 8
Electricity&Magne/smLecture18,Slide12
Wednesday, July 6, 16
ARerlong/meat0,movedto1 ARerlong/meat0,movedto2
A(erswitchmoved,whichcasehaslarger6meconstant?
A)Case1B)Case2C)Thesame
CheckPoint 8
Electricity&Magne/smLecture18,Slide12
Wednesday, July 6, 16
A)Case1B)Case2C)Thesame
CheckPoint 10ARerlong/meat0,movedto1 ARerlong/meat0,movedto2
Immediatelya(erswitchmoved,inwhichcaseisthevoltageacrosstheinductorlarger?
Electricity&Magne/smLecture18,Slide13
Wednesday, July 6, 16
A)Case1B)Case2C)Thesame
CheckPoint 10ARerlong/meat0,movedto1 ARerlong/meat0,movedto2
Immediatelya(erswitchmoved,inwhichcaseisthevoltageacrosstheinductorlarger?
Electricity&Magne/smLecture18,Slide13
Wednesday, July 6, 16
A)Case1B)Case2C)Thesame
CheckPoint 10ARerlong/meat0,movedto1 ARerlong/meat0,movedto2
Immediatelya(erswitchmoved,inwhichcaseisthevoltageacrosstheinductorlarger?
Electricity&Magne/smLecture18,Slide13
I0 is V/R in both casesA) VL(0) = I0*2RB) VL(0) = I0*3R
Wednesday, July 6, 16
A)Case1B)Case2C)Thesame
CheckPoint 12ARerlong/meat0,movedto1 ARerlong/meat0,movedto2
A(erswitchmovedforfinite6me,inwhichcaseisthe
currentthroughtheinductorlarger?
Electricity&Magne/smLecture18,Slide14
VL
τ1τ2
Wednesday, July 6, 16
A)Case1B)Case2C)Thesame
CheckPoint 12ARerlong/meat0,movedto1 ARerlong/meat0,movedto2
A(erswitchmovedforfinite6me,inwhichcaseisthe
currentthroughtheinductorlarger?
Electricity&Magne/smLecture18,Slide14
VL
τ1τ2
Wednesday, July 6, 16
A)Case1B)Case2C)Thesame
CheckPoint 12ARerlong/meat0,movedto1 ARerlong/meat0,movedto2
A(erswitchmovedforfinite6me,inwhichcaseisthe
currentthroughtheinductorlarger?
Electricity&Magne/smLecture18,Slide14
A) τ1 = L/2RB) τ2 = L/3R
VL
τ1τ2
Wednesday, July 6, 16
R1
LV
R2
R3
Calculation
Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.
WhatisdIL/dt,the6merateofchangeofthecurrentthroughtheinductorimmediatelya(erswitchisclosed
Electricity&Magne/smLecture18,Slide15
Wednesday, July 6, 16
ConceptualAnalysis
R1
LV
R2
R3
Calculation
Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.
WhatisdIL/dt,the6merateofchangeofthecurrentthroughtheinductorimmediatelya(erswitchisclosed
Electricity&Magne/smLecture18,Slide15
Wednesday, July 6, 16
ConceptualAnalysisOnceswitchisclosed,currentswillflowthroughthis2-loopcircuit.
R1
LV
R2
R3
Calculation
Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.
WhatisdIL/dt,the6merateofchangeofthecurrentthroughtheinductorimmediatelya(erswitchisclosed
Electricity&Magne/smLecture18,Slide15
Wednesday, July 6, 16
ConceptualAnalysisOnceswitchisclosed,currentswillflowthroughthis2-loopcircuit.KVRandKCRcanbeusedtodeterminecurrentsasafunc6onof6me.
R1
LV
R2
R3
Calculation
Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.
WhatisdIL/dt,the6merateofchangeofthecurrentthroughtheinductorimmediatelya(erswitchisclosed
Electricity&Magne/smLecture18,Slide15
Wednesday, July 6, 16
ConceptualAnalysisOnceswitchisclosed,currentswillflowthroughthis2-loopcircuit.KVRandKCRcanbeusedtodeterminecurrentsasafunc6onof6me.
StrategicAnalysis
R1
LV
R2
R3
Calculation
Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.
WhatisdIL/dt,the6merateofchangeofthecurrentthroughtheinductorimmediatelya(erswitchisclosed
Electricity&Magne/smLecture18,Slide15
Wednesday, July 6, 16
ConceptualAnalysisOnceswitchisclosed,currentswillflowthroughthis2-loopcircuit.KVRandKCRcanbeusedtodeterminecurrentsasafunc6onof6me.
StrategicAnalysisDeterminecurrentsimmediatelya(erswitchisclosed.
R1
LV
R2
R3
Calculation
Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.
WhatisdIL/dt,the6merateofchangeofthecurrentthroughtheinductorimmediatelya(erswitchisclosed
Electricity&Magne/smLecture18,Slide15
Wednesday, July 6, 16
ConceptualAnalysisOnceswitchisclosed,currentswillflowthroughthis2-loopcircuit.KVRandKCRcanbeusedtodeterminecurrentsasafunc6onof6me.
StrategicAnalysisDeterminecurrentsimmediatelya(erswitchisclosed.Determinevoltageacrossinductorimmediatelya(erswitchisclosed.
R1
LV
R2
R3
Calculation
Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.
WhatisdIL/dt,the6merateofchangeofthecurrentthroughtheinductorimmediatelya(erswitchisclosed
Electricity&Magne/smLecture18,Slide15
Wednesday, July 6, 16
ConceptualAnalysisOnceswitchisclosed,currentswillflowthroughthis2-loopcircuit.KVRandKCRcanbeusedtodeterminecurrentsasafunc6onof6me.
StrategicAnalysisDeterminecurrentsimmediatelya(erswitchisclosed.Determinevoltageacrossinductorimmediatelya(erswitchisclosed.DeterminedIL/dtimmediatelya(erswitchisclosed.
R1
LV
R2
R3
Calculation
Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.
WhatisdIL/dt,the6merateofchangeofthecurrentthroughtheinductorimmediatelya(erswitchisclosed
Electricity&Magne/smLecture18,Slide15
Wednesday, July 6, 16
IL = 0
Calculation
Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.
R1
LV
R2
R3
Electricity&Magne/smLecture18,Slide16
Wednesday, July 6, 16
WhatisIL,thecurrentintheinductor,immediatelyaRertheswitchisclosed?
A)IL = V/R1 up B)IL = V/R1 down C)IL = 0
IL = 0
Calculation
Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.
R1
LV
R2
R3
Electricity&Magne/smLecture18,Slide16
Wednesday, July 6, 16
WhatisIL,thecurrentintheinductor,immediatelyaRertheswitchisclosed?
A)IL = V/R1 up B)IL = V/R1 down C)IL = 0
IL = 0
Calculation
Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.
R1
LV
R2
R3
Electricity&Magne/smLecture18,Slide16
Wednesday, July 6, 16
A)B)C)D)
Calculation
IL(t = 0 +) = 0
Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.
R1
LV
R2
R3
WhatisthemagnitudeofI2,thecurrentinR2,immediatelya(ertheswitchisclosed?
Electricity&Magne/smLecture18,Slide17
Wednesday, July 6, 16
A)B)C)D)
Calculation
IL(t = 0 +) = 0
Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.
R1
LV
R2
R3
WhatisthemagnitudeofI2,thecurrentinR2,immediatelya(ertheswitchisclosed?
Electricity&Magne/smLecture18,Slide17
Wednesday, July 6, 16
IL(t = 0 +) = 0 I2(t = 0 +) = V/(R1+ R2+ R3)
Calculation
Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.
R1
LV
R2
R3
I2
Electricity&Magne/smLecture18,Slide18
Wednesday, July 6, 16
IL(t = 0 +) = 0 I2(t = 0 +) = V/(R1+ R2+ R3)
Calculation
Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.
R1
LV
R2
R3
I2
A)B)C)D)E)
WhatisthemagnitudeofVL,thevoltageacrosstheinductor,immediatelya(ertheswitchisclosed?
Electricity&Magne/smLecture18,Slide18
Wednesday, July 6, 16
IL(t = 0 +) = 0 I2(t = 0 +) = V/(R1+ R2+ R3)
Calculation
Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.
R1
LV
R2
R3
I2
A)B)C)D)E)
WhatisthemagnitudeofVL,thevoltageacrosstheinductor,immediatelya(ertheswitchisclosed?
Electricity&Magne/smLecture18,Slide18
Wednesday, July 6, 16
A)B)C)D)
VL(t = 0 +) = V(R2+ R3)/(R1+ R2+ R3)
Calculation
Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.
WhatisdIL/dt,the6merateofchangeofthecurrentthroughtheinductorimmediatelya(erswitchisclosed
R1
LV
R2
R3
Electricity&Magne/smLecture18,Slide19
Wednesday, July 6, 16
A)B)C)D)
VL(t = 0 +) = V(R2+ R3)/(R1+ R2+ R3)
Calculation
Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.
WhatisdIL/dt,the6merateofchangeofthecurrentthroughtheinductorimmediatelya(erswitchisclosed
R1
LV
R2
R3
Electricity&Magne/smLecture18,Slide19
Wednesday, July 6, 16
Follow Up
Theswitchinthecircuitshownhasbeenclosedforalong6me.
WhatisI2,thecurrentthroughR2?
(Posi6vevaluesindicatecurrentflowstotheright)
R1
LV
R2
R3
A)B)C)D)
Electricity&Magne/smLecture18,Slide20
Wednesday, July 6, 16
Follow Up
Theswitchinthecircuitshownhasbeenclosedforalong6me.
WhatisI2,thecurrentthroughR2?
(Posi6vevaluesindicatecurrentflowstotheright)
R1
LV
R2
R3
A)B)C)D)
Electricity&Magne/smLecture18,Slide20
Wednesday, July 6, 16
Theswitchinthecircuitshownhasbeenclosedforalong6meatwhichpoint,theswitchisopened.
WhatisI2,thecurrentthroughR2immediatelya(er
switchisopened?(Posi6vevaluesindicatecurrentflowstotheright)
Follow Up 2R1
LV
R2
R3
I2
Electricity&Magne/smLecture18,Slide21
Wednesday, July 6, 16
Theswitchinthecircuitshownhasbeenclosedforalong6meatwhichpoint,theswitchisopened.
WhatisI2,thecurrentthroughR2immediatelya(er
switchisopened?(Posi6vevaluesindicatecurrentflowstotheright)
Follow Up 2R1
LV
R2
R3
I2
Electricity&Magne/smLecture18,Slide21
A)B)C)D)E)
Wednesday, July 6, 16
Theswitchinthecircuitshownhasbeenclosedforalong6meatwhichpoint,theswitchisopened.
WhatisI2,thecurrentthroughR2immediatelya(er
switchisopened?(Posi6vevaluesindicatecurrentflowstotheright)
Follow Up 2R1
LV
R2
R3
I2
Electricity&Magne/smLecture18,Slide21
A)B)C)D)E)
Wednesday, July 6, 16
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