static electricity

• Why does the man's hair stand on end when he touches a Van de Graaff generator?

  Due to static electricity
• What are metals classified as in terms of electrical conductivity?

  Good conductors of electricity
• Why are metals good conductors of electricity?

  Electrons can easily flow through them
• What are plastic and glass classified as in terms of electrical conductivity?

  Insulators
• Why are plastic and glass insulators?

  Electrons cannot move through them
• What other material is an insulator?

  Plastic
• Why can't electrons move through cloth?

  Cloth is an insulator
• When plastic is rubbed with cloth, what moves from one to the other?

  Electrons
• What type of charge do electrons have?

  Negative charge
• When plastic is rubbed with cloth, which material do the electrons move from?

  From the plastic to the cloth
• After rubbing plastic with cloth, what charge does the cloth have?

  An overall negative charge
• After rubbing plastic with cloth, what charge does the plastic have?

  An overall positive charge
• After rubbing plastic with cloth, how does the size of the charge on the cloth compare to the charge on the plastic?

  They are equal in size
• What term do scientists use to describe the build-up of charge when insulators are rubbed?

  Static electricity
• In a Van de Graaff generator, what happens to electrons on the top plastic roller?

  Electrons pass from the roller onto the belt
• In a Van de Graaff generator, what happens to electrons at the bottom roller?

  Electrons pass off the belt and to Earth
• How does the top region of the Van de Graaff generator become charged over time?

  It becomes positively charged
• What role does the metal dome play in a Van de Graaff generator?

  It acts as a store of positive charge
• Why do the hairs on the man's head repel each other when he touches the Van de Graaff generator?

  The hairs are now positively charged
• Under what conditions can static electricity be dangerous?

  Under certain conditions it can cause a spark
• During aircraft refueling, how does electrostatic charge build up?

  As fuel flows through the refueling pipe
• During aircraft refueling, what could a spark trigger?

  An explosion
• To prevent sparks during aircraft refueling, what is done to the refueling truck and airplane?

  Both are earthed
• What does earthing the refueling truck and airplane prevent?

  Charges from building up
• When plastic is rubbed with cloth and electrons move to the cloth, what is the overall charge on the plastic?

  Overall positive charge
• What happens when two insulators are rubbed together?

  Electrons pass from one to the other
• What charge does an insulator get when it gains electrons?

  Negatively charged
• What charge does an insulator get when it loses electrons?

  Positively charged
• What is the phenomenon of charge imbalance called?

  Static electricity
• What happens to objects with opposite charges?

  They attract
• What kind of force is exerted between charged spheres that are not touching?

  Non-contact force
• What happens to objects having the same type of charge?

  They repel
• Why does hair stand on end when someone touches a Van de Graaff generator?

  Hairs repel each other
• What concept do scientists use to explain the forces of attraction and repulsion between charged objects?

  Electric field
• What does the presence of an electric field around a charged object mean?

  Another charged object will experience a force
• How do scientists visually represent an electric field?

  Using field lines
• At what angle must electric field lines be drawn to the surface of an object?

  90 degree angle
• What do the arrows on the field lines indicate?

  The direction of force on positive object
• In the case of a positive charge, what force does a positive object experience when brought near?

  A force of repulsion
• What happens to the force between charged objects as the distance decreases?

  The force gets stronger