Unit 8 - Electricity

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Unit 8 - Electricity
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Electricity

• What is electricity?
• The flow of electric charge (either protons or
  electrons)
• This flow is called current
• Electric current carries energy

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Current

• Does work
• Measure current using an ammeter
• Circuit breakers or fuses stop too much current
  from flowing.
• Types of current
• Alternating (AC) direction of current goes back
  and forth
• Example household current is AC
• Direct (DC) current flows in one direction.
• Example battery

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Electrical Conductivity

• Property of a substance its ability for current
  to pass through
• Conductors- electrons come free and can move to
  create electrical current
• allow current to pass
• metals
• Insulators- electrons are tightly bound to atoms
  and cannot move
• block current
• Usually nonmetals, some plastics, foam or rubber
• Semiconductors- in between in ability to conduct
  current
• Computer chips, LEDs, some lasers

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How does charge flow?

• Voltage-the push behind the current!
• Electric charge flows from high energy (voltage)
  to lower energy.
• Voltage is measured using a voltmeter
• All points on a wire are the same voltage.
• Voltage is reduced when energy is used.
• Supplies energy to make charges flow.

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Resistance

• Measures how easily charges flow in a material
• Factors that affect resistance
• Thickness
• Thicker wire has a lower resistance
• Length
• Longer wire has more resistance

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Ohms Law

• The relationship between amps, volts and ohms
• Current
• Unit Amps
• Symbol I
• Voltage
• Unit Volts
• Symbol V
• Resistance
• Unit Ohms
• Symbol R