Charging and Discharging Objects Remember! When an electron moves from one object to another, both objects are: Electrically charged This can happen in three ways: By friction By contact By induction

9.3 Charging by Friction Friction is when two objects are rubbed together. This is the main cause of static electricity. When two objects are charged by friction (rubbed together), electrons move and: -One object is positively charged (lost electrons) -The other is negatively charged (got electrons) POSITIVE NEGATIVE NEUTRALNEUTRAL

Charging by friction happens because: The positively charged nuclei of one of the objects pulls the electrons from the other object. Remember! Some types of matter have a stronger hold on their electrons than others. We can see this in a diagram called: The Electrostatic Series This diagram tells us the charge of each object when they’re rubbed together. Why Does It Happen?

Acetate Weak hold on electrons Glass Wool Cat’s fur, human hair Calcium, lead Silk Aluminum, zinc Cotton Paraffin wax Ebonite Plastic Carbon, copper, nickel Rubber Sulfur Platinum, gold Strong hold on electrons POSITIVE CHARGE NEGATIVE CHARGE

Examples of Charging By Friction Some examples we know: - hair and balloon - walking on a carpet - clothes in a dryer Other examples: -Pumping gasoline through a hose at a gas station -Air rushing over the body of a car or an airplane