statics

Learning goals We are learning what causes static electricity. We are learning to use the electrostatic series. We are learning the difference between insulators and conductors.

Electrically charged particles Location Proton + nucleus Electron - outside nucleus Neutron atoms are neutral: #protons = #electrons

Static charges charge gained when electrons move static electricity: electric charge that builds up on surface of an object charge fixed in one location on surface until given path to escape more protons than electrons = positive charge more electrons than protons = negative charge

Is the object neutral, positive or negative? How many electrons would need to be added to make the object negative?

Friction and electron movement friction: the force resisting the relative motion of two surfaces in contact rubbing two objects together electrons can transfer when objects rubbed together

Electron affinity the tendency of a substance to hold on to electrons higher material listed: tendency to lose electrons transferred to material lower in list

Learning check Where are electrons in the atom? What does “static” mean in “static electricity”? What happens when two objects made out of different materials are rubbed together? What term describes an atom’s tendency to hold on to electrons? In each of the following pairs, state which one is more likely to give up electrons: wood or human hair ebonite or silk cotton or paper

It’s the laws … law of attraction: particles with opposite charges attract each other law of repulsion: particles with like charges repel each other increase the amount of charge on objects, the attraction or repulsion increases

If the object shown in figure 2 were brought close to the object in figure 4, would they attract each other, repel each other, or have no interaction? Explain why.

Coulomb (C) Charles-Augustin de Coulomb – French physicist (1736-1806) worked with electric charges unit for electric charge named after him 1 coulomb = 6.24 X 1018 electrons added to or removed from a neutral object

Insulators and conductors conductivity: the ability of materials to allow electrons to move freely in them insulator: materials that hold onto electrons and do not allow them to move easily conductor: allow electrons to change positions conduction: the movement or transmission of electrons through a substance

water with dissolved minerals conductivity Conductors Fair Conductors Insulators copper water with dissolved minerals rubber aluminum moist air wood iron human body plastic mercury carbon pure water other metals soil metal oxides (rust)

Learning check a) What does the law of attraction state? b) What does the law of repulsion state? What is a coulomb? Define “electrical insulator.” What does “conduction” mean? a) Name two examples of good conductors. b) Name two examples of fair conductors. c) Name two examples of insulators.

Learning goals We are learning what causes static electricity. We are learning to use the electrostatic series. We are learning the difference between insulators and conductors.