Static Electricity

• What are the three types of electric charge a particle can have?

  Positive, negative, or neutral
• What type of charge do electrons have?

  Electrons are negatively charged particles
• How does the charge of a neutral atom balance out?

  The number of electrons equals the number of protons
• What happens to the overall charge of an atom when the number of electrons equals the number of protons?

  The overall charge of the atom becomes zero
• What occurs when an object gains electrons?

  The object becomes negatively charged
• What occurs when an object loses electrons?

  The object becomes positively charged
• What type of force do charged particles exert on each other?

  They exert either an attractive or repulsive force

  
• What determines whether two charged objects attract or repel each other?

  It depends on whether their charges are opposite or the same

  
• What is the saying that helps remember the behavior of opposite charges?

  “Opposites attract”
• What is charging by friction?

  • Charging occurs when certain insulating materials are rubbed against each other
  • One material gains a net positive charge, the other gains a net negative charge
  • Example: Rubbing a plastic rod with a cloth

  
• What happens to the charges of insulating materials when they are rubbed together?

  One gains a net positive charge and the other gains a net negative charge
• What is the result of rubbing a polyethene rod with a cloth?

  The rod becomes positively charged and the cloth becomes negatively charged

  
• What causes charging by friction?

  It occurs due to the movement of electrons
• What happens to the cloth when electrons are transferred from the polyethene rod?

  The cloth gains electrons and becomes negatively charged

  
• What happens to the polyethene rod when it loses electrons?

  The rod becomes positively charged
• What is the difference between electricity and static electricity?

  • Electricity involves the movement of charge in a circuit (conductors)
  • Static electricity is caused by a build-up of stationary charge on a surface (insulators)
• What are some examples of static electricity?

  • Accumulation of dust particles on surfaces
  • Hair sticking up after combing with a plastic comb
  • Rubbing a balloon and sticking it to a wall
  • Sparking

  
• What happens when charged objects are brought near each other?

  Forces of attraction or repulsion can be observed

  
• What occurs when two objects with different types of charge come together?

  A force of attraction is observed
• What occurs when two objects of the same type of charge come together?

  A force of repulsion is observed

  
• How does rubbing a balloon on a woollen jumper affect the balloon's charge?

  The balloon becomes negatively charged and the jumper becomes positively charged
• What happens when a negatively charged balloon is placed near an uncharged wall?

  The electrons on the balloon repel the electrons on the wall's surface

  
• What causes a spark to occur between two objects?

  A large potential difference between the two objects
• What can happen when a person with a build-up of charge touches an earthed metallic object?

  A spark occurs as the charge flows

  
• What is an example of sparking in everyday life?

  Feeling a small electric shock when touching a metal door handle

  
• What are the dangers of sparking?

  • Electrocution (e.g., by lightning)
  • Ignition of a fire or explosion by a spark
• How does lightning occur?

  It occurs due to the movement of electrons between ice crystals in clouds

  
• What happens to the charges in a cloud during a storm?

  The top of the cloud becomes positively charged, and the bottom becomes negatively charged

  
• What is the potential difference between the cloud and the ground during a lightning strike?

  It can become very large, around $10^8 \text{ V}$
• What causes a spark to discharge from a cloud to the ground?

  The negative charges jump to meet the positive charges on the ground

  
• How can sparking be dangerous during refuelling of aeroplanes?

  • Static charge can build up as fuel passes through a pipe
  • A spark could ignite the fuel and cause an explosion

  
• How can the risk of sparking be reduced when refuelling a plane?

  • Connect a bonding line to the Earth
  • Allows excess charge to dissipate and travel to the ground

  
• What is the purpose of the bonding line during refuelling?

  It carries excess charge to the Earth and removes the risk of sparks

  
• What is an earthed conductor?

  A wire that allows a current to flow to the Earth
• Why does current flow from an insulator to the Earth through a copper wire?

  Because copper has a lower resistance than a person
• What can happen when the potential difference between two objects becomes very large?

  The electric field may become strong enough to cause the breakdown of air
• What is an electrical discharge?

  A large spark that allows current to flow through the air
• What are the extreme examples of sparking?

  • Lightning
  • Electrical discharge in devices like Van de Graaff generators
• What can cause a spark to ignite an explosion or fire?

  A spark may ignite when close to a flammable gas or liquid
• What happens during the refuelling of aeroplanes that poses a danger?

  A build-up of static charge can occur due to friction