REVISION NOTES

IGCSE Edexcel Physics

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2.3 Energy Charge

2.3.1P Identify common materials that are electrical conductors or insulators, including metals and plastics

Conductors:

  • Copper
  • Aluminium
  • Gold
  • Silver
  • Iron

Insulators:

  • Glass
  • Air
  • Plastic
  • Rubber
  • Wood

2.3.2P Practical: investigate how insulating materials can be charged by friction

Apparatus needed:

  • Polythene (plastic) rod
  • Rods made from different insulating materials
  • Multiple cloths
  • Cradles
  • Strings
  • Wooden stands

Independent variable: Material of rod

Dependent variable: Charge of rod

Method:

  • Attach the polythene rod to a wooden stand and let it hang from the string and cradle
  • Attach another rod to another wooden stand and let it hang from the string and cradle
  • Rub both ends of the polythene rod with a cloth
  • Rub both ends of other rod with same cloth
  • If the rods move towards each other they are oppositely charged
  • If the rods rotate away from each other they have the same charge

Controlled variables:

  • Time spent rubbing each rod
  • Type of cloth
  • Length of rod
  • Size of cloths

2.3.3P explain how positive and negative electrostatic charges are produced on
materials by the loss and gain of electrons

Controlled variables:

  • Time spent rubbing each rod
  • Type of cloth
  • Length of rod
  • Size of cloths

2.2.4 Describe the qualitative effect of changing resistance on the current in a circuit

When an object loses electrons, it becomes positively charged

  • Due to the object originally having a neutral charge
  • Electrons have a negative charge
  • Thus taking away negative charge from a neutrally charged object will make it positively charged
  • 0 – (-1) = +1

When an object gains electrons, it will become negatively charged

  • Due to the object originally having a neutral charge
  • It gains negatively charged electrons
  • 0 + (-1) = -1

2.3.5P Know that there are forces of attraction between unlike charges and forces of repulsion between like charges

2.3.6P Explain electrostatic phenomena in terms of the movement of electrons

  • Opposite charges will attract in order to balance out
  • Thus protons and electrons will be attracted to each other
  • Thus objects with more protons than electrons and objects with more electrons than protons will be attracted to each other
  • This is called an electrostatic force of attraction
  • Sometimes electrons will travel from one material to another
    • Such as from the cloth to the polythene rod

2.3.7P Explain the potential dangers of electrostatic charges, e.g. when fuelling aircraft and tankers

  • When an aircraft flies through the air friction causes it to become charged with static electricity
  • When the aircraft lands the electricity wants to ground itself
  • This can happen as a spark or a flash of electricity
  • If this happens during refuelling of the aircraft it could cause an explosion
  • A solution is to earth the aircraft with a good conductor as soon as it lands

2.3.8P Explain some uses of electrostatic charges, e.g. in photocopiers and inkjet printers