static and charge

• What occurs when electrons build up on an object?

  Static charge
• On what types of objects can static charge build up?

  Insulators like plastic or wood
• Why can't static charge build up on conductors?

  Electrons flow away, forming current
• What happens when a static charge is discharged?

  An electric current flows through the air
• What happens to electrons when a plastic rod is rubbed with a duster?

  Electrons are transferred between materials
• What charge does the material gain when it receives electrons?

  Negatively charged
• What charge does the material lose when it gives away electrons?

  Positively charged
• What surrounds all charged objects?

  An electric field
• How do electric field lines behave around charged objects?

  Leave positive objects and enter negative ones
• What indicates the strength of an electric field?

  Proximity of electric field lines
• How can electric fields be demonstrated?

  By sprinkling semolina onto castor oil
• How can you tell if an object is charged?

  By seeing if it repels another charged object
• What happens when a negatively charged plastic object is near paper?

  The paper becomes positively charged and attracted
• What is the interaction between opposite charges?

  They attract one another
• What happens when like charges are near each other?

  They repel one another
• How can you demonstrate attraction and repulsion of charges?

  Using plastic rods charged with a duster
• What are the key characteristics of electric fields?

  • Surround all charged objects
  • Field lines leave positive charges and enter negative charges
  • Field strength is greatest where lines are closest
• What are the effects of static charge on objects?

  • Can attract uncharged insulators
  • Can cause repulsion between like charges
  • Can cause attraction between opposite charges