Static electricity

• Static electricity

  Occurs when insulating materials are rubbed together, causing one material to become positively charged and the other negatively charged
• Charging of materials

  1. Electrons are scraped off one material and dumped on the other

  2. One material becomes positively charged, the other negatively charged
• Charged materials

  • Polythene rod
  • Acetate rod
• The way the materials become charged depends on the polarity of the charges</b>
• The charges do not move, they are static
• Static charge is caused by electrons moving away from an object, leaving it with a positive charge
• As the static charge on an object builds up

  The potential difference between the object and the earth increases
• If the static charge gets large enough

  Electrons can jump across the gap between the charged object and the earth, causing a spark
• Electrons can also jump to any earthed conductor nearby by touching it
• When an earthed conductor is touched, a charge will build up on it and travel through the person to the earth
• Increasing friction increases the amount of energy transferred and so more electrons are transferred