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Electromagnetism (S8P5 b, c)


Electromagnetism (S8P5 b, c) Physical Science Candace Black Spring, 2010 Electric Current and Magnetism Electric current produces a magnetic field. – PowerPoint PPT presentation

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Title: Electromagnetism (S8P5 b, c)

Electromagnetism(S8P5 b, c)
  • Physical Science
  • Candace Black
  • Spring, 2010

Electric Current and Magnetism
Can you identify the 3 necessary parts of a
  • Electric current produces a magnetic field.
  • The relationship between electricity and
    magnetism is called electromagnetism

  • 3 characteristics of magnetic field
  • produced by current
  • 1. Can be turned on or off.
  • 2. Direction can be reversed.
  • 3. Strength can be changed.
  • A coil of wire with a current is called a

  • A solenoid with a ferromagnetic core is called
    and electromagnet.
  • Magnetic field is produced by both the current in
    the wire and the magnetized core.
  • A strong magnet that can be turned on and off.
  • Increase strength by
  • 1. Increasing current
  • 2. Add more loops
  • 3. Place coils closer together
  • 4. Use stronger ferromagnetic material
    as core.

Uses of Electromagnets
  • Audiotapes, videotapes, computer hard drives,
    credit cards
  • Doorbell
  • Fire doors(be able to explain how these work in
    our school)
  • To lift heavy objects such as junk cars, metal
    containers such as are used in shipping, etc.

Electric Motors
  • A device that uses an electric current to turn an
  • Transforms electrical energy into mechanical

In your notes, write at least 3 things that you
can think of that use motors.
Induction of Current
  • Electric current is induced in a conductor when
    the conductor moves through a magnetic field.
  • Generating an electric current from the motion of
    a conductor through a magnetic field is called
    electromagnetic induction.
  • Current that is generated in this way is called
    induced current.

Induced Currents
  • A current consisting of charges that flow in one
    direction only is called a direct current or DC.
  • Example battery operated items charges flow
    from positive end through circuit back to
    negative end.
  • A current that flows back and forth in a circuit
    is called an alternating current or AC.
  • Example homes, buildings, schools,
  • Advantage voltage can be raised or lowered
    higher voltages can travel over longer distances
    (from power plant) then can be lowered for
    everyday use (in our homes).

  • An electric generator is a device that transforms
    mechanical energy into electrical energy.
  • A generator uses motion in a magnetic field to
    produce an electric current.
  • Electric motors use and electric current in a
    magnetic field to produce motion.
  • Generators are used in power plants with turbines
    acting as the crank.

Be able to compare/contrast generators and motors.
  • A transformer is a device that increases or
    decreases voltage. (voltage is?)
  • Consists of 2 separate coils of insulated wire
    wrapped around an iron core.
  • Two types of transformers are
  • 1. step-up transformer increases
  • voltage.
  • 2. step-down transformer decreases
  • voltage.

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