Static Electricity & Electric Charge

• Electric


  Derived from the word "electron" meaning amber.
• Static electricity is created by the transfer of charges between two materials
• Protons

  • Positively charged
  • Mass = 1.673x10^-27 kg
• The algebraic sum of all electric charges in any closed system is constant
• Matter


  Composed of atoms that have their own subatomic particles
• Changing the charge of the object only changes the empirical charge of the whole object
• Electrons

  • Negatively charged
  • Mass = 9.109×10^-31 kg
• Neutrons


  • No charge
  • Mass = 1.675x10^-27 kg
• Electric charge

  Opposites attract
• The principle of conservation of charge states that charge can move from one object to another but cannot be created nor destroyed
• Subatomic particles

  • Protons
  • Neutrons
  • Electrons
• Ionization


  Gain or loss of electrons or protons through transfer
• The concept of gaining electric charge through rubbing amber and cloth was discovered by ancient Greeks
• Conductors

  Material that allows the transfer of electric charge
• Charging by conduction

  • Permanent
  • Electrons move to the new object until that object is grounded
• Charges of electrons & protons

  • Magnitude: identical
  • Sign: opposite
• Neutral object

  An object that has no net charge
• q

  Charge
• | qe |

  1.6x10^-19 Coulumbs
• Charging by induction

  • Temporary
  • No electrons are transferred
  • Neutrality returns when the charged object is removed
  • Inducing a charge in a neutral object by moving a charged object close to it
• Insulators


  Material that doesn't permit the transfer of electric charge
• C


  Coulumb, sl unit of charge
• What is the device designed to generate static electricity?

  Van de Graff Generator
• Conduction

  • requires contact
  • same charge
  • permanent electron transfer
• Induction

  • no contact
  • opposite charge
  • temporary (no electron transfer)
• Coulumb's Law

  "The magnitude of the electric force between two point charges is directly proportional to the product of the charges & inversely proportional to the square of the distance between them"
• k=9.0x10^9 Nm²/C²
• Positive Induction

  • electrons move away, sides becomes positive
• Negative Induction

  • electrons moves closer, sides becomes negative
• Robert J. Van de Graff

  An American physicist who invented the Van de Graff Generator in the 1920's.
• Primary purpose of the Van de Graff Generator

  to produce high voltages for experiments & demonstrations in the field of physics.