Science Posse

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Electricity and Magnetism

• Science Posse
• University of Wyoming

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What is ELECTROMAGNETISM?

• The fundamental relationship between electric
  fields and magnetic fields

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Electromagnetism

• A moving electric field creates a magnetic field
  that rotates around it
• A moving magnetic field creates an electric field
  that rotates around it
• The Right Hand Rule helps describe this

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The Right Hand Rule

• First define positive electric current as flowing
  from the positive () end of a battery, through
  an electric circuit, and back into the negative
  (-) end.
• Next define a magnetic field as always pointing
  away from a North pole and towards a South pole.

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The Right Hand Rule

• Curl your fingers in the direction of the
  rotating field.
• Extend your thumb. It now points in the direction
  of the other field.
• If your fingers are curling along with a rotating
  electric field, your thumb will point in the
  direction of the magnetic field and vice versa.

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The Right Hand Rule
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The Electromagnet

• By the Right Hand Rule, a coil of wire with
  current flowing in it will create a magnetic
  field
• The strength of the magnetic field depends on
• The amount of current in a wire More current
  means stronger magnetic field
• The number of turns in the coil More turns
  means stronger magnetic field
• The material in the coil Magnetic materials
  like iron and steel make the magnetic field
  stronger

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The Electromagnet

• A simple electromagnet can be made by coiling
  some wire around a steel nail, and connecting a
  battery to it.
• As current rotates around the nail, a magnetic
  field is created with the North pole at the
  bottom and the South pole at the top

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The Electromagnet

• Electromagnets are found in many everyday objects
  such as
• Motors and generators
• Doorbells
• Speakers
• Hard drives
• VHS and Audio cassette tapes
• Telephones

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The Electric Motor

• An electric motor is a device that converts
  electromagnetic energy into mechanical energy
• It works by using special electromagnets in the
  case of the motor that create North and South
  poles that are constantly spinning in a circle.
• These spinning poles pull along magnets that are
  on the rotor (the part that spins), causing it to
  rotate

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The Electric Generator

• An electric generator works in the opposite of a
  motor it converts mechanical energy into
  electromagnetic energy
• An outside force moves magnets in a circle past
  several coils of wire.
• By the Right Hand Rule, electric currents are
  developed in the coils of wire.