Electromagnet

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Lesson 8 Electromagnet
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An Electromagnet
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Simple electromagnet
You will find that this magnet is able to pick
up small steel things like paper clips, staples
and tacks.
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(No Transcript)
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The Coil
circular magnetic field develops around the wire
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LESSON NOTES
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We have learnt that electricity must flow in a
circuit. In a battery, electricity flows from one
terminal of the battery to the other. In a house,
power flows from live to neutral. The appliance
you plug into a socket completes the circuit from
the live slot to the neutral slot, and
electricity flows through the appliance. Let's
say you plug a light bulb into the socket. The
power will flow from the live prong, through the
filament and back to the neutral prong, creating
light in the process. The fuse prevents the
wires in the wall or the outlet itself from
overheating and starting a fire. The idea behind
the earth wire is to protect the people who use
metal-encased appliances from electric shock.
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• An Electromagnet
• An electromagnet starts with a source of power
  and a wire.
• If you look at a battery, you can see that there
  are two ends,
• one marked plus () and the other marked minus
  (-).
• Electrons collect at the negative end of the
  battery, and,
• if you let them, they will gladly flow to the
  positive end.
• The way you "let them" flow is with a wire.
• If you attach a wire directly between the
  positive and negative terminals
• 3 things will happen
• Electrons will flow from the negative side of the
  battery to the positive side as fast as they can.
  
  
• The battery will drain fairly quickly (in a
  matter of several minutes).
  Normally, you
  connect some kind of load in the middle of the
  wire so the electrons can do useful work.
  
  The load might be a
  motor, a light bulb, a radio or whatever.
• A small magnetic field is generated in the wire.
• It is this small magnetic field that is the basis
  of an electromagnet.

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electromagnet. electromagnet is a coil of wire,
often wrapped around a piece of magnetic metal.
Electromagnets work on a very simple principle.
Running electrical current through wire creates a
very small magnetic field around the wire.
Coiling the wire amplifies this magnetic
field, so it has a substantial effect on any
magnetic objects around it. Just like the
magnetic field around a permanent magnet, the
magnetic field of an electromagnet has a polar
orientation -- a "north" end and and a "south"
end -- and it is attracted to iron objects. When
you hold down a doorbell button, it closes an
electrical circuit so that household current
flows through the electromagnet (or
electromagnets) by way of a transformer. The
transformer is a simple device that takes the
120-volt household current and steps it down to a
10-volt current This current is then passed
through the electromagnet wire.