Changing%20Electrical%20Energy

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Changing Electrical Energy

• Lesson 4

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Changing Electrical Energy

• Electrical devices change electric energy into a
  form of energy we can use. This change is called
  an Electrical Conversion.
• -Example A light bulb converts electrical energy
  into light energy.

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• Other useful forms of energy include heat energy,
  sound energy, and energy of motion. Consider how
  each of the following tools is used. Identify
  what form of energy is produced.

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What form of energy is produced?

• Heat

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What form of energy is produced?

• Motion

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What form of energy is produced?

• Sound

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What form of energy is produced?

• Motion
• Heat
• Sound

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Electric Motor

• An Electric Motor is a device that converts
  electricity into movement by creating an
  electromagnet. Any electrical device that has
  moving parts will have a motor of some sort.
• Example Electric tooth brush, electric drill,
  and an electric car.
•  

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Electric Heater

• An Electric Heater is a device that converts
  electricity into movement. All electrical devices
  give off some heat. A heater works by sending
  more current through a wire than it can handle.
  This causes the wire to heat up. This is
  potentially dangerous as it can start an unwanted
  fire.

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Sound

• Sound is generated in speakers by the use of
  electromagnets which are moved by changing the
  direction of the current. This causes the
  speakers to repel and attract. The movement
  creates sound.

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What is the Source?

• Electric energy comes from different sources. The
  source in an electric circuit converts another
  form of energy into electric energy. A battery
  converts chemical energy to electrical energy.

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What is the Source?

• In a flashlight, the electric energy converts to
  light energy. Power plants convert chemical
  energy or energy of motion into electrical
  energy. This energy flows through electric
  circuits into the devices you use at home.

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For the diagram to the right, add the following labels Chemical energy ? electric energy Electric energy ? light energy
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Circuit Safety

• It is important to know how to build and use a
  circuit properly. A poorly connected circuit can
  damage equipment or injure people.
• A circuit that creates a risk of damage or injury
  is called an electrical hazard.

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Lab-Find out why a badly connected circuit is an
electrical hazard.

• Safety precaution
• Do not hold the foil in place on the battery for
  more than 10 seconds.
• Clean up your work area and put away all
  equipment after this activity.

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• Procedure
• Fold the aluminum foil so that it touches both
  terminals of the battery.
• Hold the foil in place for 5 seconds. Observe
  what happens. Then remove the foil.

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What did you find out?

• Is the circuit open or closed? Open / Closed
• How do you know?
• What happens to the electric energy in this
  circuit?
•  
•  
• How could this kind of circuit be dangerous?

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Short Circuit

• When you connected the two battery terminals with
  foil, you created a short circuit. A short
  circuit is a circuit with no useful load. Instead
  of flowing through a useful load, electric
  current flows from the source through the
  conductor and back to the source.
• In a short circuit, the conductor becomes the
  load. Electric energy is converted into heat in
  the conductor. The conductor gets hot and may
  even catch fire. A hot or smoking conductor is a
  sign of a short circuit.

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Circuit A. This circuit is safe to work with. Circuit B. In this circuit, the insulation around the wire is damaged where the wires cross. This is a dangerous short circuit.
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• Why is circuit B unsafe?
•  
•  
• Why wouldnt the bulb light up if this circuit
  was created?

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Building Circuit Safety

• Safety Comes first
• Check all your equipment and replace damaged
  equipment.
• Remove all metal jewellery
• Make sure your work area is clean, dry, and
  uncluttered.

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• Connect loads in order
• Connect one end of a wire to the positive
  terminal of the battery
• Connect components one at a time
• Complete the circuit by connecting the free end
  of the last wire to the negative terminal of the
  battery.
• If you are connecting one wire to another, use
  the alligator clips to hold the wires together.

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• Face all batteries the same way
• If you are connecting batteries together, always
  connect the positive terminal of one battery to
  the negative terminal of the next battery.

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• Keep Switch off.
• Always keep the switch in the off position
  until the circuit is complete. When you are ready
  to use your circuit, turn the switch on. Turn it
  off when you are finished.

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Testing Circuits

• Imagine you have just purchased a gaming system.
  You connect all of the wires, turn it on and,...
  nothing happens. Something is not working. How
  can you identify the problem?
•  
• A Checklist is a set of questions you can use to
  check for problems. You can use a checklist to
  make sure an electric circuit is connected
  properly. If your circuit is not working, a
  checklist will help you find the problem.

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Checklist

• A circuit checklist is a set of three main
  questions.
• Is the circuit complete? Check to make sure that
  your circuit has a source, a useful load, and
  conductors.
• Is the switch closed? Check to make sure that the
  switch is in the on position.
• Are all the wires properly connected? If the
  wires are not properly connected, make sure that
  the switch is off before connecting the wires
  properly. Then close the switch and check and
  again.

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• Look at the circuit diagrams below.
• Predict whether or not you think the bulb will
  light up by using the three questions from the
  checklist.
• Set up the circuit and see if you were correct.
  If the circuit does not light up, modify it so
  that it does light the bulb.
• Draw the circuit with the lit bulb in the space
  provided.