2.4 Static Electricity

• What are the three types of electric charge?

  Positive, Negative, Neutral

  
• What type of charge do electrons have?

  Electrons are negatively charged particles
• How does a neutral atom maintain its charge balance?

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

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

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

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

  They exert either attractive or repulsive forces

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

  Whether their charges are opposite or the same
• What is the saying to remember about opposite charges?

  Opposites attract
• Why do materials become positively charged?

  Due to the loss of electrons
• What is charging by friction?

  Charging that occurs when insulating materials are rubbed together
• What happens to the charges of two insulating materials when they are rubbed together?

  One gains a net positive charge, the other a net negative charge
• What is an example of charging by friction?

  Rubbing a plastic rod with a cloth
• What causes charging by friction?

  The movement of electrons
• What happens to the polyethene rod when it is rubbed with a cloth?

  The rod loses electrons and becomes positively charged
• What happens to the cloth when a polyethene rod is rubbed with it?

  The cloth gains electrons and becomes negatively charged

  
• What is static electricity caused by?

  A build-up of stationary charge on a surface
• Give an example of static electricity in everyday life.

  Hair sticking up after combing
• 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 charges come together?

  A force of attraction is observed
• What occurs when two objects with the same 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
• What happens when a negatively charged balloon is placed near an uncharged wall?

  The balloon attracts positive charges in the wall
• What can cause sparking?

  A large potential difference between two objects
• What is an example of sparking?

  Feeling a shock when touching a metal door handle
• What happens when a person with a large build-up of charge touches an uncharged person?

  A spark occurs due to potential difference
• What is an earthed conductor?

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

  Because copper has lower resistance
• What happens when the potential difference between two objects becomes very large?

  The electric field may cause air breakdown
• What is lightning caused by?

  The build-up of charge in clouds

  
• What occurs when ice crystals in clouds rub against each other?

  Movement of electrons between them
• What happens to the charges in a cloud during a storm?

  The top becomes positively charged, the bottom negatively charged

  
• What can a spark ignite when close to flammable gas or liquid?

  An explosion or fire
• How can the risk of sparking be reduced when refueling an airplane?

  By connecting a bonding line to the Earth

  
• What does a bonding line do during refueling?

  It carries excess charge to the Earth

  
• What is an electric field?

  A region where a charged object experiences a force
• How do electric field lines behave around positive and negative charges?

  They point away from positive and towards negative charges

  
• What happens to the strength of an electric field as the distance from the charged object increases?

  The field becomes weaker further away

  
• What type of force do objects in an electric field experience?

  Electrostatic force
• What happens to the force between two like charges as they move further apart?

  The repulsive force decreases