1. statics

2. 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.

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

4. 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

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

6. 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

7. 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

8. 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

9. 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

10. 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.

11. 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

12. 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

13. 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)

14. 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.

15. 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.