Magnetism Electromagnetism

8/18/2019 Magnetism Electromagnetism

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EET103 TEKNOLOGI ELEKTRIK

KEMAGNETAN DAN

KEELEKTROMAGNETAN

Magnetism And Electromagnetism


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Kemagnetan dan keelektromagnetan

• Kemagnetan: magnet, medan magnet danfluks, domain magnet, magnet kekal, magnet

sementara.

• Keelektromagnetan: medan magnet dan aruselektrik, daya gerak magnet dan ketepuan,

keengganan litar magnet, kuantiti dan unit

magnetik, histerisis, daya elektromagnet, kilas

dalam gegelung.• Aruhan elektromagnet: voltan aruhan dalam

gegelung, hukum lenz dan aturan tangan kanan

flemming, dan arus pusar.


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KEMAGNETAN: MAGNET

• Magnetism: a force field that acts on some

materials but not on the materials

• Magnets: physical devices that possessmagnetism

• Lodestone: natural magnet


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KEMAGNETAN: MEDAN MAGNET

DAN FLUKS

• Magnetic field: the force of magnetism• lu! "#$: invisible lines of force that make

up the magnetic field

• Magnetic field is strongest at the ends of themagnet.


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Medan Magnet dan Flk!

• Most magnets have a north pole and a

south pole.• lu! leaves the north pole and enters the

south pole.• Like poles repel% unlike poles attract.


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"reat#on o$ %ole!

• &ach time the magnet is broken, a ne' pair of

poles is created


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Like poles produce a repelling force on

these held-in-place magnets. The flux

loops are distorted.

Reaction of Like Poles

S N SN


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Like poles produce a repelling force

on these held-in-place magnets.

When freed, the magnets move apart

and the distortion decreases.


S N SN


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Like poles produce a repelling force.


S N SN

The magnets move apart and the distortion decreases.


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S N SN

Like poles produce a repelling force.

The magnets move apart and the distortion decreases.


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Rea&t#on o$ nl#ke %ole!

• (nlike poles attract

each other.

• )he force of attractionis greatest 'hen the

poles are touching.


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KEMAGNETAN: DOMAIN MAGNET'

MAGNET KEKAL DAN MAGNET

SEMENTARA• Magnetic materials: materials that are attracted bymagnetic fields

• *ommon magnetic materials: iron, iron compounds

and alloys containing iron or steel

• +onmagnetic materials: materials that are not

attracted by magnets

• +onmagnetic materials does not stop magnetic flu!

• Magnetic materials have magnetic domains.

• *urrentcarrying conductors produce magnetic fields


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S N S

N S

NS N

S NS

N

S N

S

N

S

N

S N

S N

S

N

S N

S

NS N

S

N

S N

S N

S N

S N

S

N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S NS

N S N

S NS

N

S N

S

N

S N

S

N

S

N

S N

S N

S

N

S N

S

NS

N

S

N

S N S

N

S N

S N

S

N

S N

S N

S N

agnetic !omains in a agnetic "ield

!omains are randoml# arranged in this

unmagneti$ed temporar# magnetic material.

When su%&ected to a magnetic force field,the domains are aligned 'ith the field.

When the magnetic force field is removed,

the domains return to a random arrangement.

(case )*

)&M-/A/

0 MA1+&)


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S N S

N S

NS N

S NS

N

S N

S

N

S N

S N

S N

S N

S N

S

NS N

S

N

S N

S N

S N

S N

S

N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

agnetic !omains in a agnetic "ield

!omains are randoml# arranged in this

unmagneti$ed permanent magnetic material.

When su%&ected to a magnetic force field,the domains are aligned 'ith the field.

When the magnetic force field is removed,

the domains remain aligned.

(case +*

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

S N

-&/MA+&+

)MA1+&)


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• Kemagnetan: magnet, medan magnet dan fluks,domain magnet, magnet kekal, magnetsementara.

• Keelektromagnetan: medan magnet dan aruselektrik, daya elektromagnet, daya gerakmagnet dan ketepuan, keengganan litarmagnet, kuantiti dan unit magnetik, histerisis,daya elektromagnet, kilas dalam gegelung

• Aruhan elektromagnet: voltan aruhan dalamgegelung, hukum lenz dan aturan tangan kananflemming, dan arus pusar, histerisis, kilas dalamgegelung.


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KEELEKTROMAGNETAN: MEDAN

MAGNET DAN ARUS ELEKTRIK

• &lectromagnetism: production of a

magnetic field by

current flo'ing in aconductor.

• )he magnetic field

has no poles.


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Dot: &rrent $lo(#ng

ot

&ro!!: &rrent $lo(#ng#n


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←

←

←←

! i r e c t

i o n

o f c u r r e n

t

onductor

urrent in a conductor produces flux around the conductor.

larger current produces more flux.

se the left-hand rule to determine

the direction of the flux.


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Le$t )and rle

• )he direction of the flu! around a

conductor can be determined by using:


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"lux round Parallel onductors

The conductors repel

each other 'hen

the currents are inopposite directions.

→

→

→

→

→

→

For&e *et(een &ond&tor!


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→

→

→

→

→

→

The conductors repel each other 'hen the currents are in opposite directions.



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→

→

→

→

→

→




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→

→→

→

→→




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The conductors attract each other 'hen the currents are in the same direction.


←←

→ →→


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←

→ → →




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←

→ → →




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"o#l!

• )he magnetic field around a straight 'ire is not

very strong.

• A strong field can be made by coiling the 'ire

around a piece of soft iron.

• )his electromagnet is sometimes called a

solenoid.

• )he shape of the magnetic field is the same as abar magnet.


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Le$t )and rle$or &o#l!


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"o#l!

• )he strength of the magnetic field around the coil

can be increased by:

2. (sing a soft iron core "core means middle bit$.

3. (sing more turns of 'ire on the coil.4. (sing a bigger current.

• /eversing the direction of the current

'ill reverse the magnetic field direction.


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KEELEKTROMAGNETAN: DA+A

GERAK MAGNET DAN KETE,UAN

• 5aya gerak magnet "magnetomotive force,

mmf$: effort e!erted in creating a magnetic

field

• Ketepuan "saturation$: A magnetic material

is saturated 'hen an increase in mmf no

longer increase the flu! in the material.


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KEELEKTROMAGNETAN:

KEENGGANAN LITAR MAGNET

• /eluctance "keengganan litar magnet$:

opposition to magnetic flu!

• Magnetic materials are attracted to amagnet because of their lo' reluctance

• -ermeability: refers to a material6s ability to

attract and conduct magnetic lines of flu!


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"lux

Lo' Reluctance "lux Path

"lux %ends to follo' a lo' reluctance path.

/ron


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N S

dding a Lo'-Reluctance Path in

a agnetic "ield

0pposite magnetic poles produce a fluxin the air %et'een the poles.

When a lo'-reluctance path is provided,

the flux increases and is concentrated in

the lo'-reluctance path.


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magnetomotive force (mmf*

magnetic field strength ( H *

flux (φ*

flux densit# ( B*

permea%ilit# (µ*

relative permea%ilit# (1r*

2NT/T/3S N/TS

ampere-turn ( •t*

ampere-turn4meter (•t4m*

'e%er (W%*

tesla (T*

W%4(•t•m*

unitless

KEELEKTROMAGNETAN: KUANTITI

DAN UNIT MAGNETIK


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Magnetomot#-e $or&e .mm$/

• 7ase unit: ampereturn "A•t$

• ne ampereturn is the mmf created by 2A

flo'ing through one turn of a coil.


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Magnet#& F#eld Strengt) ./

• Magnetic field strength 8 field intensity 8

magnetizing force

• Amount of mmf available to create a magnetic

field for each unit length of a magnetic circuit.

• 7ase unit: ampereturn per meter "A•t9m$

length(m)t)mmf(AH•

=

ti "i ld St th (6*


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5

5

agnetic "ield Strength (6*

mmf 7 5 x 8 t 7 +9 • t

mmf 7 5 x 9 t 7 )+ • t

ore length 7 :.9 m

ore length 7 :.+ m H 7+9 • t

:.9 m7 ;: • t 4 m

H 7)+ • t

:.+ m7 ;: • t 4 m

The magnetic field strength is the same for the t'o circuits.

8 t

9 t


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Fl .2/

• 7ase unit: eber "b$

• ne 'eber is the amount of flu! change

re;uired in 2s to induce 2< in a singleconductor.


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Fl Den!#t .4/

• lu! density: the amount of flu! per unit

crosssectional area

• 7ase unit: )esla ")$• ne tesla is e;ual to one 'eber per s;uare

meter.

)area(m

flux(Wb)density(T)Flux

2=


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"lux !ensit# (


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,ermea*#l#t .5/

• -ermeability "=$: refers to ability of a

material to conduct flu!

• 7ase unit: 'eber per ampereturnmeter"b9A•t•m$

)strength(Hfieldmagnetic

density(B)Flux

)ty(Permeabili=

µ


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Relat#-e %ermea*#l#t .5r /

• /elative permeability "=r $: compares the

permeability of the material 'ith the air

• &!ample: =r of iron 8 >?? "iron carries >??times as much flu! as an e;ual amount of

air$

KEELEKTROMAGNETAN


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KEELEKTROMAGNETAN:

ISTERISIS

• @ysteresis is the tendency of a magneticmaterial to retain its magnetization.

• @ysteresis causes the graph of magnetic

flu! density versus magnetizing force toform a loop rather than a line.

• )he area of the loop represents the

difference bet'een energy stored andenergy released per unit volume of

material per cycle. )his difference is called

hysteresis loss.


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!tere!#! loo%


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!tere!#!

• Retent#-#t material6s ability to retain a certainamount of residual magnetic field 'hen the

magnetizing force is removed after achieving

saturation. ")he value of 4 at point 7 on the

hysteresis curve.$• "oer-e For&e )he amount of reverse

magnetic field 'hich must be applied to a

magnetic material to make the magnetic flu!return to zero. ")he value of at point * on the

hysteresis curve.$



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ELEKTROMAGNET

• Motor effect: the force on a 'ire in a magnetic

field 'hen current flo's through the 'ire

• ne side of the 'ire, the fields have the same

direction and repel the 'ire• n the other side, the field have opposite

directions and attract the 'ire.

• e can predict 'hich 'ay the 'ire 'ill move byusing lemings Left @and /ule


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Motor e$$e&t .&ata%lt e$$e&t/

1ambaraBah inimenggunakan

right hand ruleC

Flemm#ng6! Le$t and Rle .Motor


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Flemm#ng6! Le$t and Rle .Motor

Rle/

• (se: )o determine the direction of a force on a

current carrying conductor in a magnetic field

• )he carbon rod is +) magnetic.


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)he carbon rod is +) magnetic.

• hen no current flo's, the rod is stationary

• hen 'e turn on the current, t)e rod

e%er#en&e! a $or&e t)at make! #t mo-e.

• )he direction of the force is determined by

Flem#ng7 Le$t and Rle

KEELEKTROMAGNETAN: KILAS


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KEELEKTROMAGNETAN: KILAS

DALAM GEGELUNG

• 7 D magnetic field

• D orce

• (se lemings left hand

rule to determine


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• +o current flo'

• 7ecause of

momentum, the coil 'ill

spin

• )here is current flo',

therefore there is .

T # #l


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Tor8e #n &o#l

• )he tor;ue in coils can be determine:

(m)Ff distanced

(N)FrceF

(Nm)Tr!ueTFdT

−

−

−

=

K t d k l kt t


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• Kemagnetan: magnet, medan magnet dan fluks,domain magnet, magnet kekal, magnet sementara.

• Keelektromagnetan: medan magnet dan arus

elektrik, daya elektromagnet, daya gerak magnet

dan ketumpatan, keengganan litar magnet, kuantitidan unit magnetik, histerisis, daya elektromagnet,

kilas dalam gegelung

• Aruhan elektromagnet: voltan aruhan dalamgegelung, hukum lenz dan aturan tangan kanan

flemming


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ARUAN ELEKTROMAGNET: 9OLTAN

ARUAN DALAM GEGELUNG

/ d d > lt


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• =

/nduced >oltage

>oltage is induced 'hen conductors cut lines of flux.

?reen arro' sho's direction of conductor movement.

!ot and = sho' direction of current caused %# voltage.

No voltage is induced 'hen conductors move parallel

to the to the lines of flux.


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FARADA+6S LA

En 2F42 t'o people, Michael araday in the(K and Goseph @enry in the (H performed

e!periments that clearly demonstrated thata changing magnetic field produces aninduced &M "voltage$ that 'ould produce

a current if the circuit 'as complete.

Ef current produces a

magnetic field, 'hy can6t a

magnetic field produce a

current I

M#&)ael Farada


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• hen the s'itch 'as closed, a momentary deflection 'as

noticed in the galvanometer after 'hich the current

returned to zero.

• hen the s'itch 'as opened, the galvanometer deflected

again momentarily, in the other direction. *urrent 'as not

detected in the secondary circuit 'hen the s'itch 'as left

closed.


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• hen the s'itch is closed, the current begins to flo' andan induced magnetic field is set up around the primarycoil. )he current increases from zero to some value over ashort period of time. )he changing electrical current

produced a changing magnetic field 'hich is the cause ofthe induced current.

• hen the s'itch is opened, the current decreases 'hichresults in a decreasing magnetic field. )he result is an

induced current in the secondary circuit, in the oppositedirection. hen a constant current flo's in the primarycircuit, the induced magnetic field is constant. A constantmagnetic field does not induce a current in the secondarycircuit.


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• araday found that the induced e.m.f. increases if

"i$ the speed of motion of the magnet or coil increases.

"ii$ the number of turns on the coil is made larger.

"iii$ the strength of the magnet is increased.

An e.m.f. is made to happen "or induced$ in aconductor "like a piece of metal$ 'henever it

6cuts6 magnetic field lines by moving across

them. )his does not 'ork 'hen it is stationary. Ef

the conductor is part of a complete circuit a

current is also produced.

Farada 6! La


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Farada6! La(

• & 8 &lectromotive force "emf$• # 8 lu!

• t 8 +umber of turn

• Any change in the magnetic environment of a coil of 'ire'ill cause a voltage "emf$ to be JinducedJ in the coil. +o

matter ho' the change is produced, the voltage 'ill be

generated.

• )he change could be produced by changing the magneticfield strength, moving a magnet to'ard or a'ay from the

coil, moving the coil into or out of the magnetic field,

rotating the coil relative to the magnet, etc.

"t N# φ ∆=


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• Enserting a magnet into a coil

also produces an induced

voltage or current.

• )he faster speed of insertion9

retraction, the higher theinduced voltage.

ARUAN ELEKTROMAGNET:

http://www.answers.com/main/ntquery;jsessionid=159fei7k7g311?method=4&dsname=Wikipedia+Images&dekey=Heinrich+lenz.jpg&gwp=8&sbid=lc02b


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ARUAN ELEKTROMAGNET:

UKUM LEN;

• )herefore, if 'e move a bar magnet through a coil of 'ire,according to Lenz6s La', the generated magnetic field"JeffortJ$ 'ill oppose the magnetic field of the bar magnet")he JcauseJ that produced the induced current 'ith itsassociated magnetic field$.

Len


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Len< La( e%er#ment:

• A small force acting on the magnet causes a

changing magnetic field in the coil 'hich 'ill

induce a current.

• Ef the current flo'ed in the indicated direction, an

induced magnetic field 'ould put the south pole

opposite the north pole in the e!ternal magnet.


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• )his 'ould attract the magnet, causing it to

accelerate. )he increased speed of the magnet

'ould induce a larger current 'hich 'ould pull

even harder on the magnet and so on.• Ef 'e think about this situation, 'e see that a small

amount of 'ork input generates a larger output of

energy. )his arrangement 'ould violate the la' of

conservation of energy


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• Ef the induced current flo's in the opposite direction, theinduced current in the coil 'ould set up a magnetic field

'ith the north pole opposite to the e!ternal magnet.• En order to generate a current, 'e 'ould have to e!ert aforce that 'ould be opposed by the induced magneticfield.

• )he harder 'e push on the magnet, the more repulsion

'e6d feel from the induced magnetic field.• )o increase the energy output, 'e 'ould need to increase

the 'ork input. )his 'ould be consistent 'ith 'hat 'ekno' about the la' of conservation of energy.

Flemm#ng6! R#g)t )and rle


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Flemm#ng ! R#g)t )and rle

.Generator Rle/

• (se: )o determine the direction of the induced

emf9current of a conductor moving in a magnetic

field.

Documents

Magnetism Electromagnetism