static electricity

• rod and cloth experiment


  2 polythene rods rubbed with a cloth and brought together. 2 acetate rods are rubbed with a cloth and brought together. 1 polythene and 1 acetate rod are rubbed and brought together. like ones repel, opposite ones attract. the cloth gains electrons and the rod loses electrons, the cloth has a negative electrostatic charge and the rod has a positive electrostatic charge. this is because of friction.
• how does static electricity cause sparks?

  1. as electric charge builds up on an object, the potential difference between the object and earth increases
  2. electrons can jump across this gap if it becomes large enough. causing a spark.
  3. they can also jump to earthed conductors.