1. Electrification by Contact - Outcomes
Distinguish between the types of charge.
Generate charge by rubbing together dissimilar materials.
Demonstrate the force between charges.
Discuss the difference between conductors and insulators.
Discuss domestic applications of static electricity.
Discuss industrial hazards of static electricity.

2. Distinguish Between Types of Charge
Recall from JC science the components of atoms:
Neutrons – no charge.
Proton – positive charge.
Electrons – negative charge.
Neutrons and protons are stationary, so electrons control charge.

3. Distinguish Between Types of Charge
An excess of electrons makes an object negatively charged.
This happens when an object gains electrons.
A deficit of electrons makes an object positively charged.
This happens when an object loses electrons.
Charge, Q, is measured in coulombs (C).
One coulomb is the charge of ~6.25× electrons.
One electron has a charge of ~1.7× 10 −19 C.

4. Generate Charge Rubbing dissimilar objects together creates charge.
The friction causes electrons to be stripped from one material and deposited on another.
The object that gets electrons becomes negatively charged.
The object that loses electrons becomes positively charged.

5. Generate Charge

6. Demonstrate Force Between Charges
Rub a polythene rod with a wool cloth
Hang it in a paper sling from a wooden retort stand.
Rub a second polythene rod with a wool cloth and hold it up to the first rod.
Rub a cellulose acetate rod with a wool cloth and hold it up to the first rod.

7. Demonstrate Force Between Charges

8. Conductors vs. Insulators
An insulator is a substance through which charge cannot flow.
e.g. glass, plastics.
A conductor is a substance through which charge can flow.
e.g. most metals.

9. Domestic Applications
Dust clinging to television screens.
Static generating from clothes rubbing against skin.

10. Hazards of Static Electricity
Why do refilling stations explode?
Why do flour mills explode?