TANMS High School Curriculum: … High School Curriculum: Electromagnetism and Nano-scale Motors 4...
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TANMS High School Curriculum: Electromagnetism and Nano-scale Motors 1 Manipulating Magnetization Electric dipole moment: ___________________________________________________________________________ ___________________________________________________________________________ Magnetic dipole moment: ___________________________________________________________________________ ___________________________________________________________________________ -magnetic dipoles are largely analogous to electric dipole moments -both types of dipoles… ___________________________________________________________________ -physical separation of positive and negative charge in electric dipole moments, but… _________________________________________________________________ polarization: ___________________________________________________________________________ magnetization: ___________________________________________________________________________ -magnetic moment of an atom or material is the combination of two sources of magnetism, both arising due to the angular momentum of charged particles: -___________________________________________________________________ -___________________________________________________________________ -two types of magnetic fields Student Name _____________________ Date ______________________
Transcript of TANMS High School Curriculum: … High School Curriculum: Electromagnetism and Nano-scale Motors 4...
TANMS High School Curriculum: Electromagnetism and Nano-scale Motors
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ManipulatingMagnetization
Electricdipolemoment:
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Magneticdipolemoment:
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-magneticdipolesarelargelyanalogoustoelectricdipolemoments
-bothtypesofdipoles…
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-physicalseparationofpositiveandnegativechargeinelectricdipolemoments,but…
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polarization:
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magnetization:
___________________________________________________________________________-magneticmomentofanatomormaterialisthecombinationoftwosourcesofmagnetism,
botharisingduetotheangularmomentumofchargedparticles:
-___________________________________________________________________
-___________________________________________________________________
-twotypesofmagneticfields
Student Name _____________________ Date ______________________
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1.Hfield:
___________________________________________________________________
2.Bfield:
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-Bfieldlinesmustclose!
B=µ0(H+M)
µ0*Hrepresentsresponsefrom______________________________
µ0*Mrepresentsresponsefrom______________________________
demagnetizingfield(strayfield):
___________________________________________________________________________
-lessstrayfield,less_______________
-leadstoformationof_________________________inallbutthesmallestmagnets
-actstoreduce___________________________________
DrawtheHfieldandBfieldlinesresultingfromtheuniformlymagnetizedblockshownbelow.
Magnetization
HField
BField
SN
SN
isotropic-__________ineverydirection
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anisotropic-____________________ineverydirection
-insmallmagnets,demagnetizationenergyleadsto_________________________
crystallinematerials(singlecrystal,monocrystalline):
___________________________________________________________________________
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polycrystallinematerials:
___________________________________________________________________________
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amorphousmaterials:
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Drawthearrangementofatomsincrystalline,polycrystalline,andamorphousmaterials.
Crystalline Polycrystalline Amorphous
magnetocrystallineanisotropy-propertyof_______________magnetswhereby…
___________________________________________________________________________
-thiscancelsoutinmaterialswith___________________________________
Zeemanenergy:
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___________________________________________________________________________
E=-µ0MHcosθ
-energyisminimizedwhenmagnetizationandappliedfieldare_______________
Drawtheevolutionofthemagneticdomainstructureasanincreasinglylargemagneticfieldis
appliedtoasmallpermanentmagnet.
-(major)typesofmagneticmaterials:
1.ferromagnet(e.g.__________)-__________magnetizationinducedin__________
directionasappliedfield,material_______________magnetizationafterremovalof
appliedfield
-whatpeoplecall“____________________”
2.paramagnet(e.g.__________)-__________magnetizationinducedin__________
directionasappliedfield,material_______________magnetizationafterremovalof
appliedfield
3.diamagnet(e.g.__________)-__________magnetizationinducedin__________
directionasappliedfield,material_______________magnetizationafterremovalof
appliedfield
magnetichysteresis-a“memory”effectresultingfrom_______________________________
___________________________________________________________________________
-enablingphenomenonbehind______________________________
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Labeltheindividualmagneticdomainsofstatesathroughdwithrealisticdistributionsof
magnetizationdirection.(Stillneedtocoverbluearrowswithwhiteboxes)
(a)/(d)saturationmagnetization:
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(b)/(e)remanence:
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(c)/(f)coercivity:
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-thermalenergy_______________________________________________________
-lowtemperature-moments________________________________________
-mediumtemperature-moments________________________________________
-hightemperature-moments________________________________________
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• Nameafewreal-lifeapplicationsofmotors(ingroups):
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• ElectricMagnetic(EM)Motors:a. EMmotorsconverts__________energyinto_________energy.Thereare
mainlytwotypesofmotorsbasedonthe__________passingthrough:__________motorand________motor.
b. DCmotors:Operationprinciple:Theforceexperiencedbyamovingchargeinthemagneticfield:________
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i) Whenθ=90o,___________________ii) Whenθ=0o,achargemovesparalleltothemagneticfield,themagneticforce
_______________.iii) Ifwehaveastationarycharge,themagneticforce_________________.iv) Identifythedirectionofforceoncharge:
• Currentcarryingwireinmagneticfield:
Ifwebendthecurrent-carryingloop,whatwouldhappen?
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a. ComponentsofaDCmotor:
• Stator:
• Rotor:• Windings• Commutator:
• Brushes:
b. Thepicturebelowshowsthebasiccomponentsofamotor.Onthediagram,indicate
• Directionofthemagneticfieldaroundtherotor• Polarityofthemagnets
• Howtocalculatetheelectromagneticforceexperiencedbythewirec. Torque&TorquevariationinaDCmotor:
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• When__________passesthroughacoilplacedina__________field,_________isproducedbythe__________force,thustheDCmotorturns.
Q:Howtokeepthetorqueinthesamedirectionforunidirectionalrotation?A:_______________________________________________________Inourmotorexperiment,weusedaslightlydifferentdesign,wherewescratchoffsome
partsofthecopperwire.Inthatcase,torquevs.angleis:
Relationshipbetweengeneratedpowerandtorque:
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Question: Q:Whatwouldhappentotheforcewhenthefielddirectionisreversed?Whataboutwhenboththefielddirectionandcurrentflowdirectionarereversed?
A:Q:Domotorshaveahighorlowinductance?A:
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ElectromagneticMotorDesign
Selectthreedesignvariablestostudy.Indicateyourselectionswithacheckmark.
� #ofloopsofcopperwire
� size/shapeofrotor
� appliedvoltage(#ofAAbatteries)
� magneticfieldstrength(proximityofrotortomagnet)
� other:_____________________________________________
FirstDesignVariable:_____________________________________________
DesignVariablesHeldConstant Value
ValuesofDesignVariableUnderStudy ResultingRPM
SecondDesignVariable:_____________________________________________
DesignVariablesHeldConstant Value
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ValuesofDesignVariableUnderStudy ResultingRPM
ThirdDesignVariable:_____________________________________________
DesignVariablesHeldConstant Value
ValuesofDesignVariableUnderStudy ResultingRPM
FourthDesignVariable(optional):_____________________________________________
DesignVariablesHeldConstant Value
ValuesofDesignVariableUnderStudy ResultingRPM
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Strain-MediatedMagnetoelectricCoupling
magnetostriction-propertyofferromagneticmaterialsthatleadsto:
1.___________________________________________________________________
2.___________________________________________________________________
-most(butnotall)magnetostrictivematerialsexpandinthe_______________direction
asanappliedmagneticfield
piezoelectricity-analogoustomagnetostriction,apropertyofferroelectricmaterials(which
have______________________________afterremovalofanapplied_______________
_______________)thatleadsto:
1.___________________________________________________________________
2.___________________________________________________________________
magnetoelectriceffect-inductionof______________________________viaanapplied
____________________field
conversemagnetoelectriceffect-inductionof______________________________viaan
applied____________________field
-factorsthatinfluencehowwellstrainiscoupledattheinterface:
1.___________________________________________________________________
2.___________________________________________________________________
3.___________________________________________________________________
-ingeneral,muchbettercouplingisachievedin______________________________
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Q:Domotorshaveahighorlowinductance?A:ReviewofLenz’slawandInductance
• Lenz’sLaw:
• Inductance:(Let’salsoderivetherelationshipbetweennumberofloopsNincoil
andinductanceL)
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LossesinDCmotors:
1.2.3.
GeneratorandMotor:FirstinventedbyNicolaTesla,ACgeneratorconverts____________energyinto
____________energy.TheworkingprincipleofACgeneratorisbasedon_____________:asweturn_______________,the______________passingthroughthe_______changes,andthecurrentchangesinthecoiltoopposethechange,sothat____________isproduced.Hence,avoltageisinducedinthecoil.
(Figuresadaptedfrom:http://hyperphysics.phy-astr.gsu.edu/)[Brushlessmotor]Advantagescomparedtomotorswithbrush:Mechanism:
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Anotherexampleofasimplebrushlessmotorthat employsHalleffect:
Brushlessmotorcomponents:1) Rotor,coolingmagnet2)Statorwithcore
arrangements.2) ApplyDCtopairsofcoilswhichwillbecomeelectro-magnets
[Reference:ElectricalEngineering:conceptandapplications,SeyedAZekavat]
Servomotor(Steppermotor)
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NotesonNanomotors:
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Imagesource:https://nanohub.org/resources/13843/download/scale_of_things_26may06_6600x5100.jpg
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