Electromagnet 8.3

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    FORM 5© COPYRIGHT BY SUPER EDUCATION GROUP (J

    CHAPTER 8: Electr !"#$et8%& Fle!'$# R'# t H"$ R*le

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    CHAPTER 8: Electr !"#$et

    PREPARED BY JJ MR+EON P"#e ,© COPYRIGHT BY SUPER EDUCATION GROUP (JOHOR JAYA)

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    CHAPTER 8: Electr !"#$et

    PREPARED BY JJ MR+EON P"#e -© COPYRIGHT BY SUPER EDUCATION GROUP (JOHOR JAYA)

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    CHAPTER 8: Electr !"#$et

    8.3 Electromagnetic Induction

    1. A steady magnetic field can be produced by a Solenoid or wire carrying electric current , permanent magnet.

    2. When we move a coil without any current flow is in a magnetic field, an induced e.m.f (electromotive

    force) is produced.

    3. An flows through the conductor and this phenomenon called

    !. "lectromagnetic induction re#uires relative motion between magnet and the coil to produce an induced

    current.

    $or $igure (c),a)closing and opening switch S continuously

    b) ad%usting rheostat & (& decrease)

    $or $igure (d), oscillating the pendulum bob in the magnetic fieldWhen there is relative motion between a conductor or a magnet, the conductor cut the magneticflu' across the magnetic field lines or change of magnetic flu' occurs.

    PREPARED BY JJ MR+EON P"#e &© COPYRIGHT BY SUPER EDUCATION GROUP (JOHOR JAYA)

    induced current

    electromagnetic induction

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    CHAPTER 8: Electr !"#$et

    1. Fleming’s Right -hand rule can be use to determine the direction of the induction current produced.

    Induced e.m.f by a moving conductor

    Action Obseravtion Inferencehe wire is moved upwards alvanometer deflect to left *urrent flows in wirehe wire is moved downwards alvanometer deflect to right *urrent flows is reversedhe wire is move hori+ontally o deflection o current flows

    -agnet is moved upwards alvanometer deflect to right *urrent flows is reversed

    Induced e.m.f by coil

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    Thumb (

    First fnger ( Field

    Center fnger ( induced

    G

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    CHAPTER 8: Electr !"#$et

    Len ’s La!

    . /en+0s /aw also can be use to determine the direction of induced current produced.". /en+0s /aw states that the direction of the induced e.m.f is such that its magnetic effects always

    .the change producing.

    Faraday’s La! of electromagnetic induction

    PREPARED BY JJ MR+EON P"#e 5© COPYRIGHT BY SUPER EDUCATION GROUP (JOHOR JAYA)

    Current inducedin opposite

    No defectionon thegalvanometer

    No current is

    Magneticeld lines

    are beingcut.

    Moving the coiltowards amagnet also

    oppose

    / e$ t e N 0 le'1 ! 2etowards t ec 'l3 e$ 4 c 'l

    ec !e1 N pole %

    / e$ t e N 0 le! 2e away 4r ! t e c 'l3e$ 4 c 'l

    ec !e1 S pole %

    directly proportional

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    CHAPTER 8: Electr !"#$et

    $araday0s /aw states that the magnitude of the induced e.m.f. is .. to the rate of

    change of magnetic flu' (rate of cutting magnetic flu') e'perienced by the conductor.

    1. he magnitude of the e.m.f in a wire increases when

    i

    ii .

    iii .. .

    . he magnitude of the e.m.f in a coil#solenoid increases when

    i .

    ii .

    iii . .. .

    4. he magnitude of induced current depends oni. he magnitude of the induced e.m.f

    ii. the resistance of the circuit

    $%%lications of electromagnetic induction

    A generator is basically the inverse of a motor. here are many coils of wire wound that can rotate in a

    magnetic field. he a'le is turned by some mechanical such as ..,. or wind turbine.

    2 he dc generator and ac generator ma5e use of electromagnetic induction to produce 6nduced e.m.f ,

    thus produce the induced current.

    PREPARED BY JJ MR+EON P"#e 6© COPYRIGHT BY SUPER EDUCATION GROUP (JOHOR JAYA)

    The wire is moved aster

    ! stronger magnet is used

    The length o wire in e.m eld is

    The relative motion between magnet and coil is

    increased

    The number o turns on coil is increased

    alling water steam

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    CHAPTER 8: Electr !"#$et

    DC Generator

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    H"$ le t r t"te

    "plit ringscommutato

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    CHAPTER 8: Electr !"#$et

    AC Generator

    Dr" t e #r"0 4 *t0*t c*rre$t 4r ! t e "c #e$er"t r " 2e

    PREPARED BY JJ MR+EON P"#e 8© COPYRIGHT BY SUPER EDUCATION GROUP (JOHOR JAYA)

    Change o rates omagnetic u is ma imum

    • !nduced e"m" is ma imum

    / e$ c 'l1 '1 "t 't1 r'9 $t"l

    0 1't' $#$ $

    %&$$

    No changes o magneticu

    / e$ c 'l1 '1 "t 't1 2ert'c"l 0 1't' $

    %%$$ 1'$ $

    ()$ $

    #andle

    / e$ c 'l1 '1 "t 't1 r'9 $t"l

    0 1't' $

    Change o rates o magneticu is ma imum

    • !nduced e"m" is ma imum$%&e '(&e)

    #$ $

    %&$$

    / e$ c 'l1 '1 "t 't1 2ert'c"l

    0 1't' $

    %%

    No changes o magneticu

    • No induced e"m" isinduced

    $ $ 1'$ $

    ()$ $

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    C*rre$t3 I;A

    C*rre$t3 I;A

    C*rre$t3 I;AC*rre$t3 I;A

    T'!e3 t;1

    CHAPTER 8: Electr !"#$et

    Alternating and direct current $a"c'd"c)

    AC Current DC CurrentGraphs

    Direction

    Examples of sources and symbols1 ac generator

    % dynamo

    ( home plug

    1 dc generator

    % dry cells ** batteries

    ( electrolyte cells

    PREPARED BY JJ MR+EON P"#e <© COPYRIGHT BY SUPER EDUCATION GROUP (JOHOR JAYA)

    T'!e3 t;1

    T'!e3 t;1

    T'!e3 t;1

    &ariable constant

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    CHAPTER 8: Electr !"#$et

    PREPARED BY JJ MR+EON P"#e ,=© COPYRIGHT BY SUPER EDUCATION GROUP (JOHOR JAYA)