Grade 8 Friction and Static Electricity

Content (from CAPS document)

Exam Guidelines

Suggested activities and investigations (from CAPS document)

Resources

Friction and static electricity: 1 week

  • Friction (rubbing) between certain materials (e.g. plastic, Perspex, glass, nylon, wool, silk, cotton) transfers electrons between atoms of two materials being rubbed together
  • When atoms lose electrons, the substance/object obtains a positive charge, causing a gain of electrons and a negative charge on the other object (only electrons move, protons and neutron do not)
  • Like charges repel each other
  • Opposite/unlike charges attract each other
  • Discharge of electrons causes sparks and shocks of static electricity, especially when air is dry
  • Lightning is a massive discharge

Rub a PVC or Perspex ruler with wool, nylon, silk or cotton. Bring the ruler close small pieces of paper, sawdust or clean hair. Observe what happens and describe in terms of same or opposite electrostatic charges on the materials.

CAPS do not require that learners know which material rubbed with a specific type of cloth will have a positive or negative charge; however, it can be done as an expansion of the required work.