ELECTRICITY

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ELECTRICITY
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Static Electricity

• Static electricity is when a charge is built up
  on an object. The charges do not move. This is
  usually caused by friction. Examples feet
  rubbing against the carpet, combing hair,
  rubbing a plastic strip with a cloth.

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Static Electricity

• Static electricity cannot hurt.
• Static electricity does not supply any useful
  energy.

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There are 3 types of charges.

• Positive
• Negative
• Neutral This means that there is no net charge
  on the object. There are equal numbers of and
  charges.

• Opposite charges will attract.
• Like charges will repel.
• Neutrally charged objects are attracted by both
  -.
• This is a very strong force.

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Conductors and Insulators

• A conductor is a substance that allows current to
  flow through it.
• Examples copper most other metals, graphite,
  the human body

• An insulator is a substance that does not allow
  current to pass through it easily.
• Examples plastic, rubber, glass, wood.

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Current Electricity

• Current is when the charges are moving. The
  movement allows them to do work for us.
  Examples lightning, a shock from a
  door knob, current in a wire

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Current

• Current can cause pain and/or be fatal. Care is
  required.
• Current also supplies a great deal of useful
  energy.

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Characteristics of Current
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Voltage

• The amount of energy carried by the electrons
  moving through the circuit.
• Measured in volts (v)
• 1 volt 1 joule per coulomb of charge
• The voltage is set by the energy source. Example
  a 1.5 volt battery or a 110 volt wall socket

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Current

• The flow of electrons through a conductor.
• Measured in amperes (amps)
• 1 amp 1 coulomb per second
• Set by the appliance.

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Resistance

• The tendency of a material to resist the flow of
  charges.
• Measured in ohms (W)
• The filament in a light bulb has a high
  resistance. This is why it gets so hot it glows.

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Series and Parallel Circuits
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Series Circuits

• In a series circuit all the current must flow
  through every appliance in the circuit. If one
  of the appliances goes out, they all go out.
  Notice that the energy seems to run out.

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Series Circuit
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Parallel Circuit

• In a parallel circuit the current flow splits up
  and goes to different parts of the circuit. If
  one bulb or appliance goes out, the rest stay on.
  All bulbs are equally bright.

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Parallel Circuit
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Schematic Diagrams
Series Circuit
Parallel Circuit
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Direct Current (DC) Alternating Current (AC)
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Direct Current

• Direct current is when the electrical current
  moves in one direction all the time.
• Examples batteries

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Alternating Current

• Alternating current is when the direction of the
  flow of current changes 60 times per second. It
  can be carried long distances from power plants
• Example wall sockets

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Power

• The amount of energy used in a period of time P
  energy / time
• For electricity Power voltage x current
  
  (P v x i)
  
• Units watts or kilowatts (1000 watts)

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Energy

• The ability to do work or cause change.
• For electricity Energy voltage x current x
  time (EE v x i x t) or (EE P x t)
• Units joules or kilowatt-hours