Static_Electricity.ppt
- 1. 1 of 11 © Boardworks Ltd 2009
- 2. 2 of 11 © Boardworks Ltd 2009 Static electricity is due to electric charge that builds up on the surface of an insulator, such as a plastic comb. The charge that has built up cannot easily flow away from the insulator, which is why it is called static electricity. What causes static electricity?
- 3. 3 of 11 © Boardworks Ltd 2009 All materials are made of atoms, which contain electric charges. Around the outside of an atom are electrons, which have a negative charge. An atom has equal amounts of negative and positive charges, which balance each other, so the atom has no overall charge. Where does static charge come from? The nucleus at the center of an atom contains protons, which have a positive charge. Electrons do not always stay attached to atoms and can sometimes be removed by rubbing.
- 4. 4 of 11 © Boardworks Ltd 2009 Static charge can build up when two insulating materials are rubbed together, such as a plastic comb moving through hair. Friction between the materials causes electrons to be transferred from one material to the other: One material ends up with more electrons, so it now has an overall negative charge. One material ends up with fewer electrons, so it now has an overall positive charge. How does static charge build up?
- 5. 5 of 11 © Boardworks Ltd 2009 Friction can be used to create a static charge. The insulator ends up with an overall negative charge. The insulator ends up with an overall positive charge. How can static charge be created? If an insulator is rubbed with a cloth, it can become charged in one of two ways: Electrons move from the cloth to the insulator. Electrons move from the insulator to the cloth. OR
- 6. 6 of 11 © Boardworks Ltd 2009 Charging materials
- 7. 7 of 11 © Boardworks Ltd 2009 Static charge – true or false?
- 8. 8 of 11 © Boardworks Ltd 2009 What are the forces between charges? The forces between charges can be investigated using rods made of insulating materials. What happens when two positively-charged acetate rods are placed near each other? The rods repel each other because they have the same overall charge. What will happen if one rod is replaced with a charged polyethylene rod? rods repel each other acetate rods
- 9. 9 of 11 © Boardworks Ltd 2009 How do opposite charges behave? When a charged acetate rod is placed near a charged polyethylene rod, the rods attract each other. The polyethylene rod has an overall positive charge and the acetate rod has an overall negative charge. The overall charges of these rods are opposite and so they attract each other. rods attract each other polyethylene rod acetate rod Why does this happen?
- 10. 10 of 11 © Boardworks Ltd 2009 Investigating pairs of charges
- 11. 11 of 11 © Boardworks Ltd 2009 Experimenting with static charge
Editor's Notes
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