Static Electricity Basic Units of Matter is the atom.   Three main units compose the atom. Electrons Protons Neutrons The science of static electricity - Anuradha Bhagwat 3:38

Electrons – has negative charge and is outside of nucleus e- Protons – has positive charge and is located in the nucleus p Neutrons – has no charge and is located in the nucleus   n   Do you remember Bohr’s atomic model?

e- e- p n p n n p n e-

Protons are not readily removed from the nuclei of atoms.   Protons and Neutrons are massive compared to electrons. The electrons are more loosely bound outside the nucleus. Therefore electrons (e-) rather than protons are transferred in a charging process.

Electric Charge There are two kinds of electric charge:  An object with a deficiency of electrons is charged positively (+).   An object with an excess of electrons is charged negatively (-).

So what do you already know about charged particles? - Like Charges repel - Unlike charges attract - Charge is quantized (use whole numbers) - Charge is Conserved

Conductors – metals – allow charges to move about more easily Insulators – the flow of electrical charge is reduced, insulators hold their charge   Conductors – metals – allow charges to move about more easily  Remember what Static Electricity is. Static Electricity – electric charges at rest – unequal distribution of electrons

Air is a good insulator. Under certain conditions the electrons can be taken off of molecules of air and become free to move. Static charges are more evident in dry environments. Water molecules in the air will attract charges balancing out the electrons.

Acrylic Rod and Cloth Rubber Rod and Fur    electrons transfer electrons transfer to the cloth from the rod from the fur to the rod Diagrams of charging materials Use overhead or white board

Conservation of Charge - - the net charge in a closed system is constant. Charging by Contact - – electrons are directly transferred Charging by Induction - – electrons are redistributed in an object without contact.

Ground - - an object that can give up or accept electrons without becoming charged enough to measure.

Ground - - an object that can give up or accept electrons without becoming charged enough to measure.

In electrical engineering, ground or earth is the reference point in an electrical circuit, it is a direct physical connection to the Earth. Electrical circuits may be connected to ground (earth) for several reasons. Exposed metal parts are connected to ground to prevent user contact with dangerous voltage if electrical insulation fails. Connections to ground limit the build-up of  static electricity  when handling flammable products or  electrostatic-sensitive devices.