Physics - Topic 11 - Static Electricity

• What is a property of all matter?

  Static electricity
• What types of charges exist?

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

  They cancel out, forming a neutral body
• What do like charges do?

  Like charges repel each other
• What do opposite charges do?

  Opposite charges attract each other
• What do insulators do regarding electricity?

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

  Their electrons cannot flow throughout the material
• What can conduct electricity?

  Conductors
• Why can conductors conduct electricity?

  Their electrons can flow and are not fixed
• What happens when two insulators are rubbed together?

  They can be charged by friction
• What occurs during the charging of insulators by friction?

  Electrons are transferred from one object to the other
• What charge forms on the object that loses electrons?

  A positive static charge forms
• What charge forms on the object that gains electrons?

  A negative static charge forms
• What determines which object loses or gains electrons?

  It depends on the materials involved
• What occurs when enough charge builds up and objects are close but not touching?

  Sparking occurs
• What is the spark that occurs during sparking?

  It is when the charge jumps through the air to balance out the charges
• What causes lightning?

  A massive spark jumps across to balance the charge difference between clouds and the Earth
• What force do charged objects experience?

  Electrostatic force
• How does the magnitude of charge affect the electrostatic force?

  Greater charge results in a greater force
• How does distance affect the electrostatic force?

  Closer together results in a greater force
• What type of force is electrostatic force?

  It is a noncontact force
• What happens when a positively charged balloon is near a wall?

  It attracts electrons in the wall
• What is the result of the induction caused by a positively charged balloon near a wall?

  The balloon sticks to the wall
• What happens when a comb is charged?

  It induces the opposite charge in small pieces of paper
• What is earthing?

  It allows electrons to flow to the earth, removing excess charge
• What is the purpose of earthing?

  It allows materials to stay neutral
• How are insecticide sprays charged when sprayed from aircraft?

  They are given a charge
• What is the effect of charging insecticide spray droplets?

  The droplets repel each other
• Why is it important for insecticide spray droplets to spread evenly?

  To avoid the risk of some droplets blowing away or falling unevenly
• What danger can occur if charge builds up while fueling cars?

  A spark could ignite and cause a massive explosion
• How can static charge build up during fueling?

  As fuel passes through a hose to the vehicle
• What is done to prevent sparks during fueling?

  The hoses are earthed
• What is an electric field?

  It 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
• How do electric fields behave around positive and negative charges?

  They point away from positive charges and towards negative charges
• How does the strength of a charge affect electric field lines?

  The stronger the charge, the more field lines present
• What type of electric field do parallel plates create?

  They create a uniform field
• What are the key concepts of static electricity?

  • Static electricity is a property of all matter.
  • Positive and negative charges exist.
  • Like charges repel, and opposite charges attract.
  • Insulators do not conduct electricity, while conductors do.
  • Charging by friction occurs when insulators are rubbed together.
  • Sparking occurs when enough charge builds up.
  • Electrostatic forces are experienced by charged objects.
  • Earthing allows excess charge to flow to the earth.
• What are the applications and dangers of static electricity?

  Applications:

  • Insecticide sprays are charged to spread evenly.

  Dangers:

  • Sparks during fueling can ignite fuel, causing explosions.
• What are the characteristics of electric fields?

  • Electric fields are regions where electric charges experience forces.
  • They point away from positive charges and towards negative charges.
  • The strength of the field is indicated by the number of field lines.
  • Parallel plates create a uniform electric field.