20.1 Electric Charge and Static Electricity
Reading Focus
Key Concepts
What produces a net electric charge?- What determines whether an electric force is attractive or repulsive?
- What determines the strength of an electric field?
- What are three ways in which charge is transferred?
- How does a static discharge occur?
Vocabulary
electric charge
electric force
electric field
static electricity
law of conservation of charge
induction
Reading Strategy
Identifying Main Ideas Copy the table below. As you read, write the main idea for each topic.
| Topic | Main Idea |
|---|---|
| Electric Charge | An excess or shortage of electrons produces a net electric charge. |
| Electric Forces | a.____________________ |
| Electric Fields | b.____________________ |
| Static Electricity | c.____________________ |
Figure 1 Electric charge is responsible for clothes that stick together when they are removed from a dryer.
Think back to the last time a thunderstorm swept through your area. A bolt of lightning streaked across the sky, followed moments later by the crash of thunder. Have you ever wondered what causes lightning? Perhaps you've observed something similar on a smaller scale closer to home. When you take clothes out of a dryer, some of them can stick together, like the sock and shorts in Figure 1. If you pull the clothes apart in a darkened room, you can see sparks that are like tiny bolts of lightning. This shouldn't be surprising once you realize that lightning and “static cling” have a similar cause the movement of electric charges.
Electric Charge
Recall that electrical energy is the energy associated with electric charges. But what exactly is electric charge? Electric charge is a property that causes subatomic particles such as protons and electrons to attract or repel each other. There are two types of electric charge, positive and negative. Protons have a positive charge and electrons have a negative charge. Electric charges move in a flash through a lightning bolt. Electric charges attract one another in clothes taken from the dryer. Although charged particles are too small to see, just about everything in your daily life is affected by charge in one way or another.
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