rators Ge & Transform rs ne e
Points to takeaway:
ne Ge rators takeadvantageof induction to produce e ctric curre by changing them tic flux through le nts agne wireloops. im ne rnating curre (AC), but nt S plege rators producealte can bem odifie to produceDCcurre d nts. ne nz Motors and ge rators haveback EMF; this is Le law in action. e vice Transform rs areinduction de s that can change voltageand curre nt.
Ge rators ne
ple ne Thesim st ge rator contains a loop of fixe sizethat rotate in a d s uniformm tic fie agne ld. e Therotation is dueto som e rnal sourceof e rgy; burning xte ne coal or natural gas, falling wate r, e tc. s agne Therotation cause them tic flux through theloop to vary; induce curre to flow. s nt
Ge rators ne
m scribe by d Mathe atically, this situation is de Faradays law, E = -N / t What is causing thechangein flux? ntation varie in tim , s e Theloops orie = BA cos t agne Therateof changeof them tic flux is /t = -BA sin t
Exam ple
-loop ge rator has a m tic fie of 0.5 T, ne agne ld A single 2 a loop are of 0.01 m , and a rotation spe d of 40 a e rad/s. rpe ld I f theloop starts out pe ndicular to thefie dire ction at t=0, whe doe theflux e n s qual 0? axim What is them umrateof changein theflux? n s Whe doe this occur?
Ge rators ne
havior is why wege alte t rnating curre from nt This be sim ge rators. ple ne d s Theinduce EMF continuously change from positiveto ne gative E = NBA sin t
E0 = NBA
E0 = -NBA
2 Pe Discussion rson
-loop ge rator has a ne A single m tic fie of 0.5 T, a loop agne ld 2 are of 0.01 m , and a rotation a spe d of 40 rad/s. e axim What is them umEMF? I f theEMF follows thecurveto theright, whe is it m um n axim ? e ro? At what tim s is theEMF ze
Back EMF
agne ld Any rotating loop of wirein a m tic fie e rie s an induce EMF. xpe nce d atureof a m will e rie otor xpe nce n I particular, thearm a back EMF. d nt s nt Theinduce curre oppose thecurre that flows through thearm atureand cause it to rotate think s ; about Le law and thehappy coil rule nz . ase e ase Back EMF incre s as therotation spe d incre s.
Exam ple
otor rate You havea DCm that ope s at 60 V and has a total re sistanceof 2.0 . nt atureright whe the n What is thecurre in thearm m is activate otor d? ct m te otor You conne an am e r to them onceit is running at a constant rateand find that thecurre nt is 6.0 A. What is theback EMF in them otor?
Transform rs e
e s Transform rs changevoltage and curre whilem nts aintaining constant powe r. re ty The area varie of transform r size and shape e s s. e All transform rs work through m utual induction.
Transform rs e
d ar ach Two coils of wireareplace ne e othe r. e re I n practical transform rs, the is also an iron corethat is share be e d twe n thecoils. rnating curre drive nt n An alte through onecoil (calle theprim d ary) cause a fluctuating m tic fie s agne ld that induce an alte s rnating curre in nt theothe coil (calle these r d condary).
Transfo...