# chapter 6: electricity - static electricity. a discharge is the movement of static electricity from

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• Chapter 7Chapter 6

Aurora Borealis is another name for Northern Lights.

• CHAPTER 6

Electricity

How do we use electricity?

280280

• Lesson 1

Static Electricity

PAGE 284 Lesson 2

Electric Circuits

PAGE 296 Lesson 3

Using Electrical Energy

PAGE 308 4 PS 1. Electricity and magnetism are related effects that have many useful applications in everyday life.

281281

• Literature Poem

ELA R 4.3.2. Identify the main

events of the plot, their causes, and the infl uence of each event on future actions. ELA W 4.2.3. Write information reports.

282

• BBENJAMINENJAMIN FFRANKLINRANKLIN

An excerpt from a poem by Rosemary and

Stephen Vincent Benét

Write About It Response to Literature This poem shows how Ben Franklin made an incredible discovery. Do

research online to find out more about Ben Franklin

and electricity. Then write a report. Include facts

and details from more than one source.

- Journal Write about it online @ www.macmillanmh.com

Ben Franklin made a pretty kite and flew it in the air

To call upon a thunderstorm that happened to be there,

And all our humming dynamos and our electric light

Go back to what Ben Franklin found, the day he flew his kite.

From A Book of Americans

Huge dynamos like

these produce electricity

283

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• Static Electricity

Lesson 1

Lightning bolts flash through the sky. You rub a balloon against your clothing and it sticks to a wall. What do lightning bolts and rubbed balloons have in common?

4 PS 1.e. Students know electrically charged objects attract or repel each other.284 ENGAGE

• Step

Step

How do rubbed balloons interact? Make a Prediction How do balloons rubbed with wool or plastic wrap interact?

Test Your Prediction Inflate two balloons. Then tie a piece of string to the end of each balloon.

Rub a wool cloth 20 times against one of the balloons. Rub the other balloon 20 times with plastic wrap.

Experiment Holding the strings, bring the balloons near each other. Observe what happens. Record the result.

Predict What would happen if you rubbed both balloons with the wool and held them near each other?

Experiment Test your prediction. Record the result.

Draw Conclusions How do balloons interact when rubbed with wool or plastic wrap?

Explore More What do you think would happen if you rubbed both balloons with plastic wrap? What would happen if you held one of the rubbed balloons near other objects? Plan a test and try it.

Materials

● 2 balloons

● 2 pieces of string, 25 cm each

● wool cloth

● plastic wrap

4 IE 6.c. Formulate and justify predictions based on cause-and-effect relationships.

285 EXPLORE

• C Main Idea Some particles of matter have a negative or positive charge. Opposite charges attract each other. Like charges repel each other.

C Vocabulary electrical charge , p. 286

static electricity , p. 288

discharge , p. 290

conductor , p. 292

insulator , p. 292

-Glossary @ www.macmillanmh.com

Charged

particles in the

girl’s hair are

attracted to the

charged balloon. C

What is electrical charge? Have you ever seen lightning flash during a

storm? Have you watched a baseball game under the bright ballpark lights? If so, then you have seen electricity in action. Electricity powers lights, ovens, and computers. Electricity makes your clothes stick together when you take them out of the clothes dryer.

Just what is electricity? That’s not so easy to answer. There are different kinds of electricity, but all electricity is the result of electrical charges. To understand electrical charge, you have to start with matter. Everything around you is made of matter. This book is made of matter. You are made of matter. Like color and hardness, electrical charge is a property of matter.

4 PS 1.e

286 EXPLAIN

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• Positive and Negative Charges There are two types of electrical

charges. These charges are called positive and negative. You cannot see or feel electrical charge the way you can see color or feel hardness. However, you can observe how charges interact with each other. A positive charge and a negative charge attract, or pull, each other. Positive charges repel, or push away, each other. Negative charges repel each other, too.

Quick Check

Main Idea How do negative charges interact? How do a negative charge and a positive charge interact?

Critical Thinking How would two neutral balloons interact?

A Over 2,500 years ago, Greeks

discovered that amber rubbed with

fur attracted feathers. In fact, the

word electricity comes from the ancient Greek word for amber.

When two objects touch, charged particles can move from one object to the other. Negative charges move more easily than positive charges. Some objects, such as wool, are likely to give up negative charges. Other objects, such as plastic wrap, are likely to accept negative charges.

A Two positive (+) charges repel each

other. So do negative (-) charges.

Opposite charges attract each other.

particles. Some of these particles are positively charged. Others are negatively charged. Most matter has the same number of positive charges as negative charges. The positive and negative charges cancel each other out. This means that the matter is neutral (NEW•truhl)—it has no overall electrical charge.

287 EXPLAIN

• What is static electricity? Suppose you rub a balloon with a

wool cloth. Negative charges would move from the wool to the balloon. This would produce a buildup of negative charges in the balloon. A buildup means that it has more of one kind of charge than the other. The buildup gives the balloon an overall negative charge. The wool would be left with a buildup of positive charges. The buildup of electrical charges on an object is called static electricity .

You know that charged particles can move between objects when the objects touch. Even more charged particles can move when objects rub against each other. Rubbing objects together causes them to touch in more places. Rubbing produces a larger buildup of charge.

A Negative charges move between

clothes in a dryer. A positively

charged sock will stick to a

negatively charged shirt.

Why are two of the balloons attracted to each other?

Clue: Count the positive and negative charges in each balloon.

Overall Charge

A Neutral A Positively

Charged

A Negatively

Charged

288 EXPLAIN

• Charged particles moving from one object to another produce a buildup of electrical charge. Charged particles moving inside an object can also produce a buildup of charge.

When you hold a negatively charged balloon near a wall, it repels the negative charges in the wall. It also attracts the positive charges in the wall. This pull makes the balloon “stick” to the wall.

Producing Static Electricity Tear a piece of tissue paper into small pieces.

Give a comb a negative charge by running it through your hair about ten times.

Observe Hold the comb near the tissue paper. What happens?

A The charges in the balloon cause

charges in the wall to move. The

balloon is then attracted to the wall.

Quick Check

Main Idea What causes static electricity?

Critical Thinking Why do dog and cat hairs stick to your clothes?

Experiment Repeat steps 2 and 3, running the comb through your hair 20 times, then 30 times.

Draw Conclusions What difference did you notice when you combed your hair more than ten times? Why does this happen?

289 EXPLAIN

• A Charges build up inside a

plasma ball. The spark you

see is an electrical discharge.

What is an electrical discharge?

It is a dry winter day. You shuffle across a carpet and touch a doorknob. Zap! You get an electrical shock.

When you walk across a carpet, electrical charges from the carpet build up on your body. You become negatively charged. When you touch a metal doorknob, the negative charges move from your body into the doorknob. You receive a small shock from the discharge of static electricity. A discharge is the movement of static electricity from one object to another.

Lightning Lightning is the discharge of

static electricity inside a storm cloud. Lightning can occur between a cloud and the ground, between two clouds, or between two oppositely charged parts of one cloud.

D The shock you get from

a metal doorknob is a

discharge of static electricity.

290 EXPLAIN

• How Lightning Forms

Lightning Safety Storms are full of wind and

moisture. Water droplets in the clouds bump and rub against one another. Some droplets become positively charged and move to the t