topic 11 - static electricity

• What can happen when insulating materials are rubbed together?

  They can become electrically charged.
• Why can insulators become electrically charged when rubbed together?

  Electrons transfer from one material to another.
• What happens to the material gaining electrons?

  It becomes negatively charged.
• What happens to the material losing electrons?

  It becomes positively charged.
• What occurs when two electrically charged objects are brought close together?

  They exert a force on each other.
• What happens when two identically charged objects are brought close together?

  They exert a repulsive force and repel.
• What happens when two oppositely charged objects are brought close together?

  They exert an attractive force and attract.
• What needs to happen when an object builds up an electrostatic charge?

  It needs to be earthed via a conductor.
• What occurs when earthing happens through a person or animal?

  It causes an electric shock.
• Why does lightning occur?

  Clouds build up an electrostatic charge.
• What happens when the electrostatic charge in clouds becomes large enough?

  They discharge via the air to the earth.
• Why does a charged balloon stick to the wall?

  It attracts the wall's negative charge area.
• What happens with a negatively charged balloon near a wall?

  The inverse occurs with a positively charged balloon.
• How does static electricity cause danger when fuelling cars?

  • Static charge builds up from friction.
  • A spark may discharge when charge builds.
  • The spark can ignite flammable fuel.
  • Earthing the vehicle and pump resolves this.
• How does earthing remove excess charge?

  It provides a low resistance path for electrons.
• What is an electric field?

  A region where a charge experiences a force.
• In what direction do the field lines in an electric field point?

  In the direction a positive charge would move.
• Describe the appearance of electric field lines in a parallel field.

  Straight lines parallel from positive to negative.
• Which field has a stronger electric field?

  The field lines being closer together show strength.
• How can you use electric fields to explain static electricity?

  • A statically charged object generates an electric field.
  • This field attracts electrons on other objects.
  • The attraction causes a flow of charge, resulting in sparks.