This preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: Illtwolk Recording Player  znlnnsjmsnlsiwkis Eile view !nlu ﬂelp Meeung Number 719 739 558 Date: Tuesday. May 15, 2mm mg 6 58 PM, Lucamme (GMT 05 an) a .1 Pa rticipams :3 Ex
Name Julnlnﬂ “WE /LEaWIE DmE
Curl Lvrldl D5 53 PM ID7 D} PM Daniel Hale us as w m 52 w J Table of Contenu E ' mu m 24
nu ‘ 12‘ 14 DeVry University Online Physics 216 Live Lecture Week 5
Professor Daniel Hale network Recording: Plaver r 2n1nn5jllv521s,wx,5 Eile view lnla help Meeung Number 719 73a ssa Date: Tuesday, May 15, mm me 6 5a m, LucalTlme (em as an) E a
.l Participant: Ex
Name Joining lime Hem/VIE lame
CurlLyndl use; w yum: w
I DEI’llEl HElE D5153 PM ID7159 PM Adade’Dlln D7DIPM/D759PM
_ ' This week we cover the connection between
electricity and magnetism. ' This will also conclude our study of
electromagnetism for this course. mal duraan m m uz l' shew all
Tull: nu ma Du Ll B EMF an M 40
m MnnanalEMFI DD‘JD‘M
D MnnnnalEMFU DD112114 re mumsl m: “was ° We will also look at circuits a bit more and
even include some AC current into them. ° Any questions before I start? ‘ I Network kemdmg . '3 DatumenuMltm. < villi 339 PM Metwork lemming Player  2n1nns_vmsns_wu_s ﬁle Elem !nlu ﬂtlp Meeung Number: 719 739 ass Date: Tuesday. May 25, mm ma: 6: as PM, Lmlnme (GMT mm) a J Participants :s; Ex Name mining m Hem/mg ume
DENEI HEIE 06:53 PM [07:59 PM
Adam MEPDIin D7 D1 PM [D7 59 PM E M F CurlLVndi umwM/umg PM ' Our ﬁrst topic this week is induction and an EMF Jrﬂg‘aﬁmiﬂf u
' So what is an EMF? l— Shn Activity “me L Recording Start uuzuozuu Ll
' Right is sounds funny since the original term for an
EMF as Electro — Motive Force, but an EMF is really a 35:35:13; 3:33: rs mm;in m: Emmi: VOItage‘ ' They dropped the whole Electro — Motive Force thing
and nowjust call it an EMF.  Before we saw that a potential difference comes from a
distribution of charges. ' How does the EMF differ from this? ' Right, we are creating this from just the changing flux
from a magnetic ﬁeld, no charges involved! Egan 0— E 1 E]. Dacumenu ial Physicswltm network Recording Plaver r zulunsjilvszlLWKJ Eile view iniu Help Meeung Number 71; 73; 655 Date: Tuesday, May 15, zum Time s as PM, Lucal'l'inie (em as on) E
.1 Participants m Ex
Name Joining lime /LEEVll’IQ time
DEI’ilEI Hale D5 58 PM [D7 59 PM Adam Muialin D7iD1PM ID7159 PM Motional EMF l J Table of Cornell: El
Ynlal duraan D1 D1 uz ' With this now in mind let’s look at our ﬁrst way we can create
an EMF. l— 5m 5
Activitv “Me : REmrding siart an an an Ll
 With these think of a square wire with a moveable section. SESSWW“ ESE: E1 lrlmiorial EMF 1 an in 24 ' This is then placed in and perpendicular to a magnetic ﬁeld B, ETTHBIEZZI ‘ 2:13: 7
like this: A 6 i5 i EJEPM t Nam/Dr e E] Dmumenu , J ral Phyiiriwlt Mztwork Recording Player  2n1nns_Pmsns_wu_s ﬁle gm 1m ﬂtlp Meeung Number: 719 739 ass Date: Tuesday. May 25, mm ‘ﬁme: s: as PM, anmme (GMT mum) Motional EMF  ' Now what we do is move the metal rod to the right in this
case. ' So from last week we see that the force here is given as
(with q = e in this case):
F3: ev x B ' Now this must be the same as the force the electron feels,
which is FE=eE, so then they two must be equal and
opposite like this: eE= ev x B now we cancel the e to get
' E = v x B so this is the induced electric field. ' Now finally we remember that AV = EL in this case, so we
get: AV = vBL ' Questions? J Pa rticipams :s; Ex
Name Joining lime /Leavlng ume
DanielHale D6153 PM tum; PM Adam Manlln n7 n1 PM 1D7 59 PM cun Lvnm uquM tum PM —
J Table of (lolltellu B
mal duraunn: D11D11DZ Activity Recording Elan: uuzuozuu U
B Elethnmagnebsm an oz 35
m EMF mum B Mammal EMFI E549 0— ": [I [a ” ,ﬁlienevaanyslcswuc... “a r :H l EDacumenurl‘yﬁcm... network Recording] PlaVEI‘ r 2llll1I157PllV52167WK75
Eile Elew lniu Help Meeung Number 71; 73g 655 Date: Tuesday, May 15, zum Tm s as PM, Lucal'l'lme (cm as on) Motional EMF Example ' Okay now let’s do one from the Practice quiz. This time
#1 A metal rod of length 2.0 m is moved at 6.0 m/s in a
direction perpendicular to its length. A 5.0mT
magnetic ﬁeld is perpendicular to both the rod and its
velocity. If the resistance of the rod is 15 mg what is
the current in the rod? ' So what do we do?  Right, ﬁrst we need to ﬁnd AV, since I = AV/R. ' So we see that AV = vBL so we get:
AV = (6.0 m/s)(5.0 x103T)(2.Om) = 6 x 102 v
Finally: I = AV/R = 6.0 x lOZV/15 x1030: 4.0A .1 Participants m Ex
Name JDll’lll’lg lime Hem/mg lame
DEI’HEI Hale D5 58 PM [D7 59 PM Adam Mﬁalln D71D1 PM ID7159 PM Curt Lvndl D7 04PM ID7 59 PM —‘
.1 Table of Contenu El
Mal duraan n1 n1 n2 M:th
B MnﬁnnalEMFﬂ
b Motional EMF E ample B Quashans’ nunms
B Elethi: Generamrs an 19 27
B PawerPlams amuse m chum/u. s... E] ” ﬂ Genevalphyilriwlt I New :wdlng . El Dazumenurmrm lietmrk lemming Player  2n1nns_Pmsns_wu_s ﬁle Elem !nlu ﬂtlp Meeung Number: 719 739 558 Date: Tuesday. May 25, Zn)“ me: 5: as PM, meme (GMT mm) B a
J Pa rticipams :s; Eix
Name Jolnlng nme /Leavlng ume
DanlelHale uses PM tum; PM Adam McPuIln n7 n1 PM 1m 59 PM Electric Generators ' Now we can start to look at how this principle can be used to J “seamen: is
created electricity. melauramnlmmz  The main thing to remember is that it is the CHANGING ﬂux that
creates the electric ﬁeld. ' In our previous example we changed the size of the "hole" that the
ﬂux was going through. ' But you can also change this by rotating a wire (or coil of wires)
inside a large coil of wire this is creating a magnetic ﬁeld. Activity nme e
D MononalEMFU umz: 14 7
B Moﬁonal EMF Example an 15 as * E549 0— E ” ,ﬁ General Physicswuc... E]. Documenu e Micrer < LEW 3:55 PM Elli] network Recording Plaver e zumnsjmszlLWKJ Eile grew lnlu Help Meeumg Number 71; 73g 655 Date: Tuesday, May 15, znm Time s 55 PM, Lucal'l'lme (cm as on) E g
.1 Pa nicioan ts m 5*
Name Jolnlrlg nme Meal/mg lame
oemel Hale as 53 PM {D7 59 PM Adam Moialln D71D1PM/D7159 PM Power Plants ' So how many types of power plants can you
all think of? B Faraday'slaw muons m
B PamerPlamis nugsaz 7 ' Good, lots of examples (Coal, hydro — electric, 322:3;1'2" 33.2.3: m “A...” Mn 1: as gas burning, nuclear, wind power) and all of
these (solar is the only exception) use this
principle. They mechanically turn a large
turbine inside and electromagnetic and create
an EMF! Ely 4» 0— e
W. t Men :lrdlng . @Daeumenuemm. < ii?" 357 PM {a ” ﬂ Generalphyslrswlt network lemming Player  2n1nns_Pmsns_wx_s Eile grew !nfu ﬂtlp Meeung Number: 719 739 559 Dace: Tuesday. May 25, mm Wile: E: 59 PM, anl‘ﬁmE (EMT mm) B a
J Pa rticipams :r; Eix
Name Jelnlng ume /Leavlng ume
Danlel Hale uses PM tu7rs9 PM
Adam Mdelrn d7 d1 PM {B7 59 PM Fa raday’s Law ' This will help us understand the relationship between the
induced EMF and the magnetic ﬁeld. ' Just like we had with electricity there is a magnetic flux:
(qu = BA cos 6
B Quesudnew  where 9 is the angle from the perpendicular that B is with respect to the surface. J Table of (lolltellu B
rural duraudn: mzmznz l— Shaw all
Activity Tulle ‘ D PdwerPlanls 99:21:59 B Faraday‘slaw an 13 29 m m PauerPlams T ' So remember before we talked about the changingflux, so we
see that the induced EMF is given as: EMF = {MM/(At)
Or for a Coil: EMF = N(ACI)B)/(At) E549 0— e General Physrcswrc... 1 Men E]. Ddcumenu a Mum.“ < IS 9: 9:00 PM network Recording Plaver a zumnsjllvszLLWLS Eile view lnlu Help Meeurrg Number 719 739 655 Date: Tuesday, May 15, znm TIME s 55 PM, Lucal'l'lme (em as on) E g
.1 Participants m Ex
Name Jnlnlrlg lime Hem/mg lame
DEI’HEI Hale D5 58 PM [D7 59 PM
Adam Mﬁalln D71D1 PM ID7159 PM
M CurtLvndI D7D4PM/D7 59PM
—
—‘ ' These are basically the opposite of a generator: J TahleofContenIs 9 rural durahnn n1 n1 n2 ' This time we use a changing current (AC) to produce a
force of rotation on a shaft.
' Then this rotating force is where we get the motor aCtion _ ' Where are some examples of where you all can ﬁnd
electric motors? B Transfurmersl
B Transrarmerslr dug9.31 ﬂ
B Transformers Examples an 33 41
B Transformers Examples (ca... aura3:49 ' Good example, heck what about the computer you are
on right now? ' Right the CD drive and Hard Drive are examples right
there! Also all the different fans! t < ii?" 902 PM {a ” ﬂ Generalphyslriwlt E] Datumenu a g . network lemming Player  2D1ﬂns_PllV5116_WK_5 file giew !nlu ﬂtlp Meeang Numaei: 719 739 see Date: Tuesday. May 25, zinn ‘ﬁme: a: 58 PM, anl‘ﬁmE (GMT {15:00) E a
1 Pa rticipams :s; §:x
Name Joining nme Hem/mg ume
Daniel Hale D6158 PM tum; PM Adam MaPaIm n7 D1PM/D7 59 PM Transformers  ' This is a nice piece of electrical equipment that is used to stepup or _
stepdown the current or voltage in an AC system. Jﬂmwcmem B  This is basically and electrical system where a soft core piece or iron
"loop". Then you wrap wire around the different sides Total auiaunn: mzmznz [— Shu Time e W126134 ' The key is that you wrap a different number of turns around the g 31:32::mm 22:: D
primary and secondary coils. a rammeeeﬁmaee nmqw
l'h Vlﬁiiﬂnvr mmmqu V
_
anaiy Secnndary
winding winding
' NSWMS 5mm“ < :31" 9:03 PM network Recording Plaver e zumnsjilvszLLWLS Elle view Info help Meehng Number 71s 739 655 Date: Tuesday, May 15, zinc Time s 55 PM, Lual'l'inie (Gm 415 on) E g
l Participants in Eix
Name Jaimng hme nearing hmE
Daniel Hale as as PM 157 59 PM Adam Muialin D71D1PM/D7159 PM Transformers  ' So even though the changing flux can change the
current and voltage, their product is the same. ' Remember that P = IV
D TransfurmersExamples ' So since you must conserve energy (remember power isjust the energy expended per unit time) then this MUST stay constant. ' So with the primary and secondary coils we see that:
Ipr = ISVS
‘ which if we remember that V1 = N1(A<I)B)/(At) we get:
Vs/VP = Ns/NP and ls/IP = NP/Ns
' Any questions? J Table of Canteen: Ea
Tnial duraimn n1 n1 n2 I— Show a
Activity ﬁne A B Mninrs an 15 34 B rransiurmersi B Transmrmersii pas1.31 an 33 41 < 6.1!) 905 PM natumk handing Player  2n1nns_Pmsns_wu_s ﬁle Elem !nlu ﬂtlp Meeung Number: 719 739 558 Date: Tuesday. May 25, mm Wile: E: 58 PM, Lmlnme (GMT mum) Transformers Examples: ' Here are two quick examples about transformers
from the practice quiz: A transformer has 200 turns on its primary and 12 x J Participants Name Joining m /Leaving ume
Daniel HEIE 06:53 PM [07:59 PM
Adam Md’alin D7 Di PM [D7 59 PM
Curl LVl'idI DYIDQPM [07:59 PM J Table of (lolltellu B EX
mal uurauan: mzmznz l— Shaw all Activity B Transformers Examp as (:a an 39 4a
m Indutmrs aama turns on its secondary. If the input voltage is 2000 V, what is the output voltage?  Where do we start?  Right, we remember that V5/Vp = N5/NP. ' So this gives: V5 = Vp(N5/Np) = (2000V)(12/200) =
120V ' Questions? E549 0— General Physicswltm 1 Men E]. Dacumenu r Mum... network Recording Plaver r zumnsjmszlLWLS < ﬁlm 9:13 PM Eile view Info Help Maeung Number 71; 73; 655 Date: Tuesday, May 15, zum Time s 55 PM, Lucal'l'ime (am as on) Transformers Examples (cont): ' Here is another one: An ideal transformer has an input voltage of 20,000 V and an
output voltage of 260 V. If the input current is 26 A, what is the output current? .1 Participants m Ex
Name Joining lime naming lame
Damal Hala as 53 PM {D7 59 PM
Adam Mazalm Wm PM tum PM
Curt Lyman u7 mPM m7 59 PM — —‘ J Table of Contenu El
ralal durauan n1 n1 n2 Activitv B Transformers Examples B Indutmrs
B AC Circuits! an 47 1a  Where do we start? ' Right we use these equations: V5/Vp = NS/Np and Id“: = NP/NS
' So ﬁrst we need to solve for the ratio Ns/Np via the voltage
equation. 50 we see that VS/Vp = Nde gives:
(20,000V)/(260V) = 76.9 = Nsle.
' Now we use l5/IP = Np/Ns to get: IS = lple/Ns) = 26A(76.9) =2000A
E my an 0— ' E] Datumenu r {a ” ﬂ GeneralPhysiriwlt g . < 6.1!) 917 PM lietmrk neeonling Player  2n1nns_Pmsns_wu_s Eile Elem !nlu ﬂtlp Meeung Number: 719 739 558 Dace: Tuesday. May 25, am me: s: 58 PM, immme (EMT mm) B a
J Pa rticipan is i—iii x
Name JDlnlrlg ma /Leavlng ume
Darllel Hale uses PM tu7l5a PM Adam Manllrl n7 n1 PM {D7 59 PM Inductors ' Okay one more little circuit idea for this term. Total durahnn: DIIDJIDZ
' We see that in an AC circuit, there is a item called self—
inductance. ' An inductor is basically a little coil of wire. Activity
DD133142
[a an 39 40 D Transformers Examples: an .47. ID ' So the deﬁnition of the inductance (L) is: W?“ v
NED: Ll or: L=NCI)/
' For a regular coil this is given as:
L: ponZTtrZE and since N = nf, this is also:
L = (lioN2nr2)/f
' What this then means is that in an AC circuit there is a
voltage drop/gain across an inductor: EMF =  L(Al)/(At) E 5 4D 0— a E]. Dacumenu a Micrer < E m 9:20 PM ” .ﬁ lasnelaanyslcswm... 1 New, Elli] network Recording Plaver a zulunsjmszlLWLS Eile Elew lniu Help Meeting Number 719 739 555 Date: Tuesday, May 15, zum TIME s 55 PM, Lucal'l'lnie (cm as on) E g
.1 Participants in Ex
Name Julnlrlg time neaan lame
Danlel Hale as 53 PM {D7 59 PM
I _ Adam Mu7allrl U71U1 PM tum PM
AC I CunLynm u7mPM/u75aPM ° This now brings us to our next topic, AC taftttiiitfzf t
circuits. ° The main difference here is that the current W U
and the voltage sinusoidally cycle from a positive value (+\/, H) so the same negative
values (V, ). ° 50 in addition to voltage, resistance and current, now amplitude and frequency (0))
are main factors in the AC circuit. B AC Clrmlis in M5139
B AC Examples: an 57 35 , < l3" 921w netmrk Recording Player  2n1nns_Pmsns_wu_s file Elem !nlu ﬂtlp Meeung Number: 719 739 558 Date: Tuesday. May 25, am Wile: E: 58 PM, anmme (GMT mum) J Pa rticipan Is :s;
Name JDlnlng nme neaan ume
Daniel Hale D6153PM/D7159 PM
Adam Manlin n7 n1 PM {D7 59 PM AC Circuits   So this means the voltage and current are given mar duraunn: mzmznz [— Shaw all i(t) =  sin (cat) and v(t) = (an sin(oat) where l and €me and the maximum values of the current and 2332i:
voltage.  The power is then given by:
p(t) = i(t)v(t) = IV sin2((ot)
 But the average power dissipated is given as:
Pa“, = 1/2(V) = 1/2(2R)
 Make sense? Egan 0— a El Dacumenu e r < ﬁlm 9:23 PM network Recording Plaver e zulunsjmszlLWLS Eile view lnlu Help Meeting Number 71; 73; 655 Date: Tuesday, May 15, 2mm TIME s 55 PM, Lucal'l'lme (am as on) .1 Pa rticipan ts m Name Joining nme Meal/mg lame
Daniel Hale as 53 PM 1m 59 PM
Adam Muialin Wm PM tuna PM AC Circuits   Next we can see how capacitors and inductors come into play in AC J madman: a
circuits. mammaan n1 n1 n2 l— Shaw all . . . , , MEN“ Tulle ‘
' So what we see Is that the voltage drop across a capaCItor In an AC crrcurt B “mm mm
is VC = IXC where XC is called the capacitive reactance and is measured in o warmmu Ol'l ms. B AC mm
B AC Examples: an 57 35 7
' AlSO we see that Xc= 9— B QM vv159117 l—l  It is important to note that in an AC capacitor the voltage and current are M m m
out of phase by 71/2 or 900. It is said that the current leads the voltage in
this system. ' There is a similar quantity for inductance called XL where we get:  VL = XLIL and this is called the inductive reactance.  Also we see that XL = (0L ' Also again in an AC inductor the voltage and current are out of phase by
11/2 or 900. It is said that the current lags behind the voltage in this system. ' Questions? < 6.1!) 929 PM Metwork haunting Player  2n1nns_pmsns_wu_s Eng Maw wu ﬁeip Meeung Number: 719 739 ass Date: Tuesday. May 25, 20]“ ‘ﬁme: a: 58 PM, meme (GMT {15:00) E a
l Pa rticipams n; Eix
Name Juining time (Leaving time
nameIHaIe 06:53 PM tuna PM
Adam Manlin n7 n1 PM {D7 59 PM AC Examples: ' So here is an example from the Practice Quiz: ma uraunnzmzmznz [— s nwa
What is the inductive reactance of a ZOO—mH inductor Jim “L n '
attached to a 120V rms 60.0Hz source? D AC Circunsi Unii715?
3 Ac omen DD4354
' So what do we do? B ' Right we remember that XL = (0L.
 So XL: (211*60 Hz)(200 x10—3 H) = 75.4 9
' Here is another one: What is the capacitive reactance of an 8.00—pF capacitor
attached to 120V rms at 60.0 Hz? ' So what do we do?
' Right we remember that XC = 1/(0)C) so:
' xC = 1/[(2n*60 Hz)(8.0 x106 F) = 332 Q E549 0— E I Nah Dldmgm Elm manneriiumi.‘ ' < '51!) 9:30PM ai Physicswltm ...
View
Full Document
 Spring '11
 DanielHale
 Physics

Click to edit the document details