Charging by Contact 1 You can charge a

Charging by Contact 1. You can charge a neutral object by rubbing it with a different material (friction). 2. 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. electrons to be transferred from • The contact allows ______ one substance to the other substance. • One substance will gain electrons (and become negatively _______ charged) while the other will lose positively electrons (and become _______ charged). • Since the two objects have opposite charges, they will attract _______ each other.

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 11. 2 when it is rubbed with a different material. 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. 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 stronger has a _______ hold for electrons than fur. When the fur and ebonite are rubbed together, some fur ebonite electrons from the _____ move to the _______ stronger attraction for electrons. because ebonite has the ______ Since the _______ gains electrons, it becomes ebonite charged. ________ Sincenegatively the _______ loses electrons, it becomes ________ fur charged. positively

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

Electrostatic Dusters

Homework p. 477 # 1 -2 Worksheet