static elec

• Charging by friction


  Certain insulating materials become electrically charged when rubbed against each other
• Charges on insulators


  Remain on the insulators and cannot immediately flow away
• One material becomes positive


  The other becomes negative
• Example of charging by friction


  • Plastic or polythene rod being charged by rubbing it with a cloth
• Charging by friction


  • Both the rod and cloth are insulating materials
  • Negatively charged electrons are transferred from one material to the other
  • The material that gains electrons becomes negatively charged
  • The material that loses electrons is left with an equal positive charge
• When certain insulating materials are rubbed against each other, they become electrically charged
• Negatively charged electrons are rubbed off one material and on to the other
• The material that gains electrons becomes negatively charged
• The material that loses electrons is left with an equal positive charge
• When two electrically charged objects are brought close together


  They exert a force on each other
• Two objects that carry the same type of charge

  Repel
• Two objects that carry different types of charge

  Attract
• Attraction and repulsion between two charged objects


  Examples of non-contact force
• An object becomes negatively charged when it gains electrons and positively charged when it loses electrons
• When two charged particles or objects are close together


  They exert a force on each other
• Types of force between two charged objects

  • Attractive (the objects get closer together)
  • Repulsive (the objects move further apart)
• Whether two objects attract or repel


  Depends on their charge
• If the charges are opposite

  They will attract
• If the charges are the same

  They will repel