Topic 11 Static Electricity

• What is a property of all matter related to static electricity?


  Static electricity is a property of all matter.
• What types of charges exist?

  Positive and negative charges exist.
• What happens when a body has equal amounts of positive and negative charge?

  They cancel out, forming a neutral body.
• What is the behavior of like charges?

  Like charges repel each other.
• What is the behavior of opposite charges?

  Opposite charges attract each other.
• What is the characteristic of insulators regarding electricity?

  Insulators do not conduct electricity.
• Why do insulators not conduct electricity?

  Their electrons cannot flow throughout the material; they are fixed.
• What is the characteristic of conductors regarding electricity?

  Conductors can conduct electricity.
• Why can conductors conduct electricity?

  Their electrons can flow and are not fixed; they are delocalised.
• How does static electricity occur when two insulators are rubbed together?

  • Electrons are transferred from one object to the other.
  • This forms a positive charge on one object and a negative charge on the other.
• What happens when conductors are rubbed together?

  Electrons will flow in/out of them, cancelling out any effect, so they stay neutral.
• What forms a positive static charge on an object?

  A positive static charge forms on the object that loses electrons.
• What forms a negative static charge on an object?

  A negative static charge forms on the object that gains electrons.
• What determines which object loses or gains electrons when charging?

  It depends on the materials involved.
• What occurs during sparking in static electricity?

  • Sparking occurs when enough charge builds up and the objects are close but not touching.
  • The spark is when the charge jumps through the air from the highly negative object to the highly positive object to balance out the charges.
• How does lightning occur?

  • Lightning occurs when the charge difference between clouds and the Earth becomes so great.
  • A massive spark (lightning) jumps across to balance the charge.
• What force do charged objects experience?

  Charged objects experience an electrostatic force of attraction or repulsion.
• How does the magnitude of charge affect the electrostatic force?

  A greater charge results in a greater force.
• How does distance affect the electrostatic force between charged objects?

  Closer together results in a greater force; force is proportional to the inverse square of the distance.
• What type of force is electrostatic force?

  It is a noncontact force, as force can be felt even when the objects are not touching.
• What happens when a positively charged balloon is near a wall?

  • The positively charged balloon attracts electrons in the wall.
  • This induction causes the balloon to stick to the wall.
• How does a comb pick up small pieces of paper?

  • A charged comb induces the opposite charge in small pieces of paper.
  • This causes the paper to be attracted to the comb.
• What is earthing in static electricity?


  • Earthing allows electrons to flow to the earth, removing excess charge.
  • This helps materials to stay neutral.
• How are insecticide sprays charged when sprayed from aircraft?

  • The spray droplets are given a charge.
  • This causes the droplets to repel each other and spread evenly, attracting to the earth.
• What is the risk of sparks when fuelling cars?

  If charge builds up and a spark forms, it could ignite and cause a massive explosion.
• How can static charge build up during fuelling cars?

  • As fuel passes through a hose to the vehicle, a static charge can build up.
  • When it is too large, a spark might form, potentially igniting the fuel.
• How do hoses prevent static charge build-up during fuelling?

  The hoses are earthed to stop static charge from occurring.
• What is an electric field?

  An electric field is the region where an electric charge experiences a force.
• In which direction do electric fields point?

  They point in the direction a positive charge would go, away from positive charges and towards negative charges.

  
• How do electric fields relate to the strength of the charge?

  The stronger the charge, the more field lines are present and the stronger the force felt.
• What is the characteristic of electric fields between parallel plates?

  Parallel plates have a uniform electric field.
• What is the relationship between electric fields and charges?

  Electric fields are like magnetic fields for magnets.
• How do electric fields behave at right angles to surfaces?

  Electric fields point to charges at right angles to the surface.