Bellringer

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Bellringer

• What is one way to increase the strength of the
  magnetic field of a current?

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Electricity from Magnetism

• Notes

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Induction of Electric Current

• Motion can produce electrical energy. Suppose you
  move a conductor, such as a wire, through a
  magnetic field. By doing this, you will create
  an electrical current in the conductor.
• Electromagnetic induction is when an electric
  current is created in a conductor by moving the
  conductor through a magnetic field. This is
  called inducing a current. Current that is made
  by moving a conductor through a magnetic field is
  called induced current.

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Induction of Electric Current

• You can induce a current in two ways
• -You can move the conductor through the magnetic
  field.
• -You can move a magnet through a coil of wire.

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Induction of Electric Current

• An induced current may flow in only one
  direction. A current that flows in only one
  direction is called direct current, or simply DC.
• An induced current my reverse directions very
  quickly over and over again. A current that
  reverses direction repeatedly is called
  alternating current, or simply AC.

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Induction of Electric Current

• Batteries supply a direct current.
• Thomas Edison used DC in his first electric
  generating plant.

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Induction of Electric Current

• The electric circuits in homes, schools, and
  other buildings is alternating current.
• An advantage of AC over DC is that AC voltage can
  be easily raised or lowered to a higher or lower
  voltage. This means that a high voltage can be
  used to send electrical energy over great
  distances, then the voltage can be reduced to a
  safer level for everyday use.
• Nikola Tesla is credited for creating the AC
  system we use today to distribute electricity to
  the entire nation.

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Generators

• An electric generator changes mechanical energy
  into electrical energy.
• An electric generator is the opposite of an
  electric motor. Remember an electric motor
  changes electrical energy to mechanical energy.
• Generators that produce AC AC generators
• Generators that produce DC DC generators.

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Generators

• The electric company uses giant generators to
  produce energy for your home and school.

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Transformers

• Electric companies send electrical energy through
  wires at high voltages. Your home, though, uses
  electrical energy at low voltages. Transformers
  are used to change the voltage of an electric
  current.

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Transformers

• A transformer is made up of two coils of wire,
  each wrapped around an iron core.
• One coil of a transformer - called the primary
  coil - is connected to an alternating current.
  The other coil - called the secondary coil - is
  not connected to a source of electricity.

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Transformer
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A Transformer at Work

• AC flows through the primary coil of a
  transformer. This causes a magnetic field to
  change as the current alternates. The changing
  magnetic field induces a current in the secondary
  coil.

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A Transformer at Work

• A transformer can either increase or decrease
  voltage. A step-up transformer increases voltage.
  In a step-up transformer, there are more loops in
  the secondary coil than the primary coil.

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A Transformer at Work

• A step-down transformer decreases voltage. In a
  step-down transformer, there are fewer loops in
  the secondary coil than in the primary coil.

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A Transformer at Work

• Transformers allow safe transfer of electrical
  energy from generating plants to homes and other
  buildings. Step-up transformers are used to step
  up voltage in a current that comes out of a power
  plant. Step-down transformers are used to step
  down voltage before the current is used in a home.