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Electromagnetic Dynamo


The connection with the topic in the course. Currents. Magnetic fieds. Electromagnetism. Basic theory of Dynamo. Currents & Magnetic Fields ... – PowerPoint PPT presentation

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Title: Electromagnetic Dynamo

Electromagnetic Dynamo
  • Jing Hu
  • Dan Wu
  • JinHee(Ellen) Ahn
  • Yuanyuan Zhang

The connection with the topic in the course
  • Currents
  • Magnetic fieds
  • Electromagnetism
  • Basic theory of Dynamo

Currents Magnetic Fields
  • Hans Christian Oersted(1777-1851) was a physicist
    and chemist who first discovered the
    electromagnetism. He was the first person to
    notice movements of a compass needle when it was
    placed near electric fields (current carrying
    wires). This was when he realized connections
    between magnetism and electricity.

Currents Magnetic Fields
  • The changes of the compass at different places
    around the wire, proves that the magnetic field
    circulates perpendicularly to the wire. When the
    current moves upwards, the magnetic field move
    towards the right. When the current moves
    downwards, the magnetic field moves towards the

Electromagnetic Induction
  • After Oersted discovered how magnetism was
    produced by current carrying wires, it was a
    question if magnetism can produce electricity.
  • The two physicist on the right discovered the
    possibility in 1831. It was a coincidence that
    they discovered what is now Faradays Law at the
    same time because they were not aware of each
    others work.

Michael Faraday (1791-1867) United Kingdom
Joseph Henry (1797-1878) United States
Electromagnetic Induction
  • Moving a magnet in or out of coils of
    current-carrying wires can produce electricity.
  • Electricity is produced by relative motion
    between wire and magnetic field.
  • Greater number of coils can produce more
  • More difficult to move magnet when there is
    greater number of coil. Its because there is
    greater resistance between magnetic field and

Generators and alternating current
  • A simple generator.
  • Electricity is generated with the same concept
    create relative motion between a current carrying
    wire and magnetic fields.
  • Reverse position of wire and magnet electricity
    exhibited when coil of wire rotate surrounded by
    magnetic field. This method is more functional.

The history of electromagnetic generator
  • In 1831-1832 Michael Faraday discovered that
    a potential difference is generated between the
    ends of an electrical conductor that moves
    perpendicular to a magnetic field. He also built
    the first electromagnetic generator called the
    'Faraday disc', a type of homopolar generator,
    using a copper disc rotating between the poles of
    a horseshoe magnet. It produced a small DC
    voltage, and large amounts of current. Its the
    beginning of the modern dynamo.

Electrical generator
  • In 1832 Hippolyte Pixii built an early form
    of alternating current electrical generator,
    based on the principle of magnetic induction
    discovered by Michael Faraday In 1832 he built an
    early form of alternating current electrical
    generator, based on the principle of magnetic
    induction discovered by Michael Faraday. It used
    a permanent magnet which was rotated by a crank.
    The spinning magnet was positioned so that its
    north and south poles passed by a piece of iron
    wrapped with wire. Pixii found that the spinning
    magnet produced a pulse of current in the wire
    each time a pole passed the coil. Furthermore,
    the north and south poles of the magnet induced
    currents in opposite directions. By adding a
    commutator, Pixii was able to convert the
    alternating current to direct current.

Theory of the Dynamo
  • When LOAD 1 is greater than LOAD 2, the increased
    amperage flow through LOAD 1 causes DYNAMO 1 to
    act as a motor, driving DYNAMO 2 as a generator
    and transferring excess power to the other side
    onto COIL B.
  • If LOAD 2 is greater than LOAD 1, the rotor will
    spin the other direction, moving power from
    Dynamo 2 to Dynamo 1.
  • When LOAD 1 and LOAD 2 are equally balanced, the
    rotor between the two dynamos can completely stop
    moving. There are mechanical forces present due
    to the current from LOAD 1 and LOAD 2 passing
    through the respective Dynamos, but the driving
    forces perfectly balance each other out.

  • http//www.siemon.com/uk/white_papers/images/06-05
  • http//www.sciencebuddies.org/mentoring/project_id
  • http//www.pbs.org/wgbh/nova/orchid/images/amat_fa
  • http//www.nndb.com/people/671/000096383/joseph-he
  • http//sol.sci.uop.edu/jfalward/physics17/chapter
  • http//en.wikipedia.org/wiki/Dynamo
  • http//en.wikipedia.org/wiki/Electric_current
  • Text book
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