Charging by Contact

polyester carpet

Complete your anticipation guide

Charging by Contact1. 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.

polyester carpet

Charging by Contact: FRICTION

What is the charge on the hair?

What is the charge on the comb?

neutral

neutral

Before combing

What is the charge on the hair?

What is the charge on the comb?

positive

negative

After combing

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.

How do we know what charge each object will have?

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.

11.2

electrostatic series

The electrostatic series helps you determine whether an object will become positively or negatively charged when it is rubbed with a different material.

Use the electrostatic series to predict the charges on the following substances. Draw the electrons and proton charges that you would predict before and after they have been rubbed together.

1. A rubber balloon is rubbed with a wool cloth.

Before

After

Textbook assignment.