♡ Topic 11_Static electricity ♡

• When insulating materials are rubbed together, they can become (statically) electrically charged
• Insulators become electrically charged when rubbed together because:

  • Electrons transfer from one material onto the other
  • The material gaining electrons becomes negatively charged
  • The material losing electrons becomes equally positively charged
• When two electrically charged objects are brought close together, they exert a force on each other
• When two identically charged objects are brought close together, they exert a repulsive force on each other and repel
• When two oppositely charged objects are brought close together, they exert an attractive force on each other and attract
• An example of a non-contact force is the repulsive or attractive force acting between two electrically charged objects
• We feel an electric shock when an object builds up an electrostatic charge and needs to be ‘earthed’ via a conductor, causing electrons to flow to/from the earth to balance the charge. If earthing occurs through a person/animal, it causes an electric shock
• Lightning occurs when clouds build up an electrostatic charge, and when this charge becomes large enough, the clouds discharge via the air to the earth, known as lightning
• A charged balloon sticks to the wall because when a positively charged balloon is placed next to a wall, the positive charges near the balloon get repelled to other parts of the wall, leaving an area with a negative charge that attracts the positively charged balloon towards the wall, making the balloon stick
• Earthing removes excess charge by providing a path with low resistance for electrons to flow either from the device or towards the device to reduce the charge build-up
• Static electricity causes danger when fuelling cars as static charge can build up due to friction between the pipes and the fuel, leading to a spark discharge that could start a fire if it reacts with the flammable fuel. This is resolved by earthing the vehicle and pump
• An electric field is a region where an electric charge will experience a non-contact force
• In an electric field, the field lines point in the direction that a positive charge would move (experience a force)
• In a parallel electric field, the appearance of electric field lines is straight lines, parallel to each other, pointing from the positive plate to the negative plate, with partially curved lines at the edges
• The stronger field is indicated by field lines being closer together
• You can use electric fields to explain static electricity by:

  • The statically charged object generating an electric field
  • This field attracting electrons on other objects, causing a flow of charge resulting in sparks