Electrical Charge and Static Electricity

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Electrical Charge and Static Electricity

• Things that go ZAP!!!!!!!!

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Electric Charge

• Electrical energy is the energy associated with
  electric charges
• An electric charge is a property that causes
  subatomic particles such as protons and electrons
  to attract or repel each other
• Protons have a positive charge ()
• Electrons have a negative charge (-)

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Electric Charge

• When an atom gains an electron it is negatively
  charged
• When an atom loses an electron it is positively
  charged
• A net electric charge is produced when there is
  too many or too few electrons

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Coulomb

• The SI unit for electric charge is the coulomb
• It takes 6.24 x 1018 electrons to make 1 coulomb
• A lightning bolt is 10 to 20 coulombs
• A flash camera uses about 0.025 coulombs to
  produce a flash

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Electric Forces

• Like charges repel each other where opposite
  charges attract
• Electric force is the force of attraction or
  repulsion between electrically charged objects
• If you double the electric charge of an object
  you double the electric force
• If you double the distance between two objects
  the electric force is one-fourth as strong

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Electric Fields

• The electric field is the effect an electric
  charge has on other charges in the space around
  it
• The strength of an electric field depends on the
  amount of charge that produces the field and the
  distance from the charge

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Static Electricity and Charging

• Static electricity includes how charge is
  transferred between objects
• Law of conservation of charge states that the
  total charge in an isolated system is constant
• Charge can be transferred by friction, conduction
  and induction

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Friction

• An example of charging by friction is rubbing a
  balloon against your hair
• The electrons will move from your hair to the
  balloon
• The balloon now has a negative charge and your
  hair has a positive charge

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Conduction

• A Van de Graff generator ( a charged metal
  sphere) will cause a charge by contact
• There is a reduction in the charge of the Van de
  Graff generator because some has gone to the
  persons hair
• Your hair will stand on end due to the charge

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Induction

• When you go to touch a metal doorknob after
  walking across a carpet is induction
• Your hand has a negative charge from walking
  across the carpet
• The electrons in your hand repel the electrons in
  the doorknob
• Induction is a transfer of charge between
  materials without contact

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Static Discharge

• Static discharge occurs when a pathway through
  which charges can move forms suddenly
• When you go to touch the doorknob the air between
  your finger and the knob is charged
• This allows electrons to flow from your hand to
  the doorknob