Faraday

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Faradays Discovery
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• We already know that an electric current produces
  a magnetic field. Is the reverse true? Can a
  magnetic field produce an electric current?
• In 1831, Michael Faraday experimented with
  conductors in the vicinity of magnetic fields.
  From his experiments, he came up with a general
  statement

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• Faradays Law of Electromagnetic Induction
• An electric current is induced in a conductor
  whenever the magnetic field in the region of the
  conductor changes amount or direction.

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• Mutual Induction
• Occurs whenever a changing current in one coil
  induces a current in a nearby coil
• The magnitude of an induced current in a coil is
  affected by
• The number of turns on the induction coil
• The rate of change of the inducing magnetic field
• The strength of the inducing magnetic field

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Direction of Induced Current
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• A few years after Faraday published his work, a
  physicist named Heinrich Lenz applied the law of
  conservation of energy to electromagnetic
  induction.
• Lenz came up with a rule to determine the
  direction of the induced current.

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• Lenzs Law of Induced Current
• The direction of the induced current creates an
  induced magnetic field that opposes the motion of
  the inducing magnetic field.

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Electric Generators AC and DC
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• An electric generator is a device for converting
  mechanical energy into electrical energy by
  rotational motion.
• The rotational motion comes from a continuous
  source of energy, such as falling water, wind, or
  expanding steam.

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• The main components of a generator are magnets,
  an armature, brushes and either slip rings (for
  an AC generator) or a split-ring commutator (for
  a DC generator).
• A magnet attached to the end of a rotating shaft
  is positioned inside a stationary conducting ring
  that is wrapped with a continuous (and very long)
  piece of wire.

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• When the magnet rotates, it induces a small
  electric current in each section of wire as it
  passes.
• All the small currents of the individual sections
  add up to one larger current. This current is
  what is used for electric power.

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• Turbines
• In a large generator, a turbine provides the
  rotational mechanical energy for the generator.
• An electric utility power station will use a
  turbine, engine, or similar machine to drive an
  electric generator or another device that
  converts mechanical or chemical energy into
  electricity.
• Steam turbines, internal-combustion engines, gas
  combustion turbines, water turbines, and wind
  turbines are the most common methods to generate
  electricity.

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The Transformer
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• Transformers allow electricity to be efficiently
  transported over long distances.
• Transformers are composed of two or more windings
  usually wrapped around a common core made iron.
• If the current flowing through the primary coil
  is fluctuating, then a current will be induced
  into the secondary winding. A steady (DC)
  current will not be transferred from one coil to
  the other.
• The coils are usually constructed so that they
  will have a small resistance. Copper coils are
  the most common type.