Charging by Contact You can charge a neutral object by rubbing it with a different material (friction). Sometimes, you can charge an object just by touching it with another object and then separating the two objects (conduction). Electrons from one object move onto the other object.

Charging by Contact: FRICTION Before combing What is the charge on the hair? neutral What is the charge on the comb? neutral

After combing What is the charge on the hair? positive What is the charge on the comb? negative Why do the comb and hair attract? They are oppositely charged.

Charging Objects by FRICTION This method of charging objects involves rubbing two neutral objects together. The contact allows ___________ to be transferred from one substance to the other substance. One substance will gain electrons (and become ______________ charged) while the other will lose electrons (and become ______________ charged). Since the two objects have opposite charges, they will ______________ each other. electrons negatively positively attract

How do we know what charge each object will have?

The electrostatic series helps you determine whether an object will become positively or negatively charged when it is rubbed with a different material. 11.2 For two materials, look at their positions in the electrostatic series. The material closer to the top of the list will lose electrons and become positively charged. The material near the bottom of the list will gain electrons and become negatively charged. electrostatic series

Example: A piece of rabbit fur is rubbed with an ebonite rod Example: A piece of rabbit fur is rubbed with an ebonite rod. What is the charge on each object and explain how the charge was produced? If we look to the Electrostatic Series, we see that the ebonite has a ______________ hold for electrons than fur. When the fur and ebonite are rubbed together, some electrons from the __________ move to the _____________ because ebonite has the ___________ attraction for electrons. Since the _____________ gains electrons, it becomes ________________ charged. Since the _____________ loses electrons, it becomes ________________ charged. stronger fur ebonite stronger ebonite negatively fur positively

Example: If cat fur is rubbed with a glass rod The fur (having a ________________ hold on electrons) will ___________ electrons and become ____________ charged. The glass (having a _______________ hold on electrons) will ____________ electrons and become _______________ charged. stronger gain negatively weaker positively lose

Electrostatic Dusters

Homework p. 477 # 1-2 Worksheet