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Electricity & Magnetism Lecture 18 Today’s Concepts: A) Induc)on B) RL Circuits Electricity & Magne/sm Lecture 18, Slide 1 Wednesday, July 6, 16
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Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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Page 1: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

Electricity & MagnetismLecture 18

Today’sConcepts: A)Induc)on

B)RLCircuits

Electricity&Magne/smLecture18,Slide1

Wednesday, July 6, 16

Page 2: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

ExtendeddeadlineoneforFlipItPhysicshomeworkduelastnight:! 80%extendedun)lJuly10.

Wednesday, July 6, 16

Page 3: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

Stuff you said..

WilltherebemorelabacAviAesinvolvingoscilloscopes?UnlikelabacAviAesinvolvingmagnets,theoscilloscopesareforeign,new,andcuriouslyinteresAngtoplay/learnwithduetotheabove?

WhataretheexactdifferencesbetweentheCapacitorandInductor.InwhichsituaAonwouldIusetheCapacitorinsteadoftheInductororviceversa?

Wednesday, July 6, 16

Page 4: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

Stuff you said..

WilltherebemorelabacAviAesinvolvingoscilloscopes?UnlikelabacAviAesinvolvingmagnets,theoscilloscopesareforeign,new,andcuriouslyinteresAngtoplay/learnwithduetotheabove?

WhataretheexactdifferencesbetweentheCapacitorandInductor.InwhichsituaAonwouldIusetheCapacitorinsteadoftheInductororviceversa?

http://www.sfu.ca/phys/141/1154/Schedule141.pdf

Wednesday, July 6, 16

Page 5: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

Stuff you said..

WilltherebemorelabacAviAesinvolvingoscilloscopes?UnlikelabacAviAesinvolvingmagnets,theoscilloscopesareforeign,new,andcuriouslyinteresAngtoplay/learnwithduetotheabove?

WhataretheexactdifferencesbetweentheCapacitorandInductor.InwhichsituaAonwouldIusetheCapacitorinsteadoftheInductororviceversa?

http://www.sfu.ca/phys/141/1154/Schedule141.pdf

Wednesday, July 6, 16

Page 6: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 7: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

Wednesday, July 6, 16

Page 8: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

Today’s Experiment

Electricity&Magne/smLecture18,Slide2

Loop area A

Wednesday, July 6, 16

Page 9: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

Today’s Experiment

Electricity&Magne/smLecture18,Slide2

Loop area A

Wednesday, July 6, 16

Page 10: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

Today’s Experiment

Electricity&Magne/smLecture18,Slide2

Loop area A

E = ��B

dt= �A

dBdt

Wednesday, July 6, 16

Page 11: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

Today’s Experiment

Electricity&Magne/smLecture18,Slide2

Loop area A

E = ��B

dt= �A

dBdt

Wednesday, July 6, 16

Page 12: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

E = ��B

dt= �NA

dBdt

Today’s Experiment

Electricity&Magne/smLecture18,Slide2

Loop area A

E = ��B

dt= �A

dBdt

Wednesday, July 6, 16

Page 13: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 14: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

From the Prelecture: Self Inductance

Electricity&Magne/smLecture18,Slide2

Wednesday, July 6, 16

Page 15: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

Wrapawireintoacoiltomakean“inductor”…

dIdt

ε = −L

From the Prelecture: Self Inductance

Electricity&Magne/smLecture18,Slide2

Wednesday, July 6, 16

Page 16: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

currentI

L

What this really means:

Electricity&Magne/smLecture18,Slide3

Wednesday, July 6, 16

Page 17: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

currentI

L

dIdt

εL = −L

What this really means:

Electricity&Magne/smLecture18,Slide3

Wednesday, July 6, 16

Page 18: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

currentI

L

dIdt

εL = −L

emfinducedacrossLtriestokeepIconstant.

What this really means:

Electricity&Magne/smLecture18,Slide3

Wednesday, July 6, 16

Page 19: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

currentI

L

dIdt

εL = −L

emfinducedacrossLtriestokeepIconstant.

Inductorspreventdiscon)nuouscurrentchanges!

What this really means:

Electricity&Magne/smLecture18,Slide3

Wednesday, July 6, 16

Page 20: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

currentI

L

dIdt

εL = −L

emfinducedacrossLtriestokeepIconstant.

Inductorspreventdiscon)nuouscurrentchanges!

It’slikeiner)a!

What this really means:

Electricity&Magne/smLecture18,Slide3

Wednesday, July 6, 16

Page 21: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 22: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 23: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 24: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 25: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 26: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 27: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

RL

VBATT

I = 0

Whennocurrentisflowingini)ally:

How to think about RL circuits Episode 1:

VL

Electricity&Magne/smLecture18,Slide5

Wednesday, July 6, 16

Page 28: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

RL

VBATT

I = 0

Whennocurrentisflowingini)ally:

How to think about RL circuits Episode 1:

VL

Electricity&Magne/smLecture18,Slide5

Wednesday, July 6, 16

Page 29: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 30: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 31: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 32: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 33: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 34: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 35: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 36: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 37: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 38: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 39: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 40: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 41: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 42: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 43: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 44: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 45: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

R

I

L

Why is there Exponential Behavior?

Electricity&Magne/smLecture18,Slide10

Wednesday, July 6, 16

Page 46: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

R

I

L+

+

Why is there Exponential Behavior?

Electricity&Magne/smLecture18,Slide10

Wednesday, July 6, 16

Page 47: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

R

I

V = IRL+

+

Why is there Exponential Behavior?

Electricity&Magne/smLecture18,Slide10

Wednesday, July 6, 16

Page 48: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

R

I

V = IRdIdtV = L L

+

+

Why is there Exponential Behavior?

Electricity&Magne/smLecture18,Slide10

Wednesday, July 6, 16

Page 49: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

R

I

V = IRdIdtV = L L

+

+

Why is there Exponential Behavior?

Electricity&Magne/smLecture18,Slide10

Wednesday, July 6, 16

Page 50: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

R

I

V = IRdIdtV = L L

+

+

Why is there Exponential Behavior?

Electricity&Magne/smLecture18,Slide10

where

Wednesday, July 6, 16

Page 51: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

R

I

V = IRdIdtV = L L

+

+

Why is there Exponential Behavior?

VL

Electricity&Magne/smLecture18,Slide10

where

Wednesday, July 6, 16

Page 52: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

Prelecture:

RL

I

Lecture:

VLVBATT

Electricity&Magne/smLecture18,Slide11

Wednesday, July 6, 16

Page 53: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

Prelecture:

RL

I

Lecture:

VLVBATT

Didwemessup?

Electricity&Magne/smLecture18,Slide11

Wednesday, July 6, 16

Page 54: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

Prelecture:

RL

I

Lecture:

VLVBATT

Didwemessup?

No:Theresistanceissimplytwiceasbiginonecase.

Electricity&Magne/smLecture18,Slide11

Wednesday, July 6, 16

Page 55: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

ARerlong/meat0,movedto1 ARerlong/meat0,movedto2

A(erswitchmoved,whichcasehaslarger6meconstant?

A)Case1B)Case2C)Thesame

CheckPoint 8

Electricity&Magne/smLecture18,Slide12

Wednesday, July 6, 16

Page 56: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

ARerlong/meat0,movedto1 ARerlong/meat0,movedto2

A(erswitchmoved,whichcasehaslarger6meconstant?

A)Case1B)Case2C)Thesame

CheckPoint 8

Electricity&Magne/smLecture18,Slide12

Wednesday, July 6, 16

Page 57: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

A)Case1B)Case2C)Thesame

CheckPoint 10ARerlong/meat0,movedto1 ARerlong/meat0,movedto2

Immediatelya(erswitchmoved,inwhichcaseisthevoltageacrosstheinductorlarger?

Electricity&Magne/smLecture18,Slide13

Wednesday, July 6, 16

Page 58: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

A)Case1B)Case2C)Thesame

CheckPoint 10ARerlong/meat0,movedto1 ARerlong/meat0,movedto2

Immediatelya(erswitchmoved,inwhichcaseisthevoltageacrosstheinductorlarger?

Electricity&Magne/smLecture18,Slide13

Wednesday, July 6, 16

Page 59: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 60: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 61: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 62: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 63: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

R1

LV

R2

R3

Calculation

Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.

WhatisdIL/dt,the6merateofchangeofthecurrentthroughtheinductorimmediatelya(erswitchisclosed

Electricity&Magne/smLecture18,Slide15

Wednesday, July 6, 16

Page 64: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

ConceptualAnalysis

R1

LV

R2

R3

Calculation

Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.

WhatisdIL/dt,the6merateofchangeofthecurrentthroughtheinductorimmediatelya(erswitchisclosed

Electricity&Magne/smLecture18,Slide15

Wednesday, July 6, 16

Page 65: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

ConceptualAnalysisOnceswitchisclosed,currentswillflowthroughthis2-loopcircuit.

R1

LV

R2

R3

Calculation

Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.

WhatisdIL/dt,the6merateofchangeofthecurrentthroughtheinductorimmediatelya(erswitchisclosed

Electricity&Magne/smLecture18,Slide15

Wednesday, July 6, 16

Page 66: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 67: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 68: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 69: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 70: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 71: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

IL = 0

Calculation

Theswitchinthecircuitshownhasbeenopenforalong6me.Att = 0,theswitchisclosed.

R1

LV

R2

R3

Electricity&Magne/smLecture18,Slide16

Wednesday, July 6, 16

Page 72: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 73: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 74: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 75: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 76: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 77: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 78: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 79: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 80: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 81: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

Follow Up

Theswitchinthecircuitshownhasbeenclosedforalong6me.

WhatisI2,thecurrentthroughR2?

(Posi6vevaluesindicatecurrentflowstotheright)

R1

LV

R2

R3

A)B)C)D)

Electricity&Magne/smLecture18,Slide20

Wednesday, July 6, 16

Page 82: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

Follow Up

Theswitchinthecircuitshownhasbeenclosedforalong6me.

WhatisI2,thecurrentthroughR2?

(Posi6vevaluesindicatecurrentflowstotheright)

R1

LV

R2

R3

A)B)C)D)

Electricity&Magne/smLecture18,Slide20

Wednesday, July 6, 16

Page 83: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

Theswitchinthecircuitshownhasbeenclosedforalong6meatwhichpoint,theswitchisopened.

WhatisI2,thecurrentthroughR2immediatelya(er

switchisopened?(Posi6vevaluesindicatecurrentflowstotheright)

Follow Up 2R1

LV

R2

R3

I2

Electricity&Magne/smLecture18,Slide21

Wednesday, July 6, 16

Page 84: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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

Page 85: Electricity & Magnetism Lecture 18 - SFU.ca Lecture 18 - Induction.pdf · Electricity & Magne/sm Lecture 18, Slide 6 Wednesday, July 6, 16. What is the current I through the ver/cal

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