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  • Electricity and Magnetism

    www.sciencea-z.com

    Written by David Dreier

    Visit www.sciencea-z.com

    Electricity and Magnetism

    A Science AZ Physical Series

    Word Count: 2,278

  • Written by David Dreier

    www.sciencea-z.com

    Key elements Used in this BooKthe Big idea: Since the late 1800s, electricity has brightened our homes and streets, powered our appliances, and enabled the development of computers, phones, and many other devices we rely on. Understanding what electricity is and how it becomes ready for our safe use helps us appreciate this energy source. Without magnets, we couldnt generate electricity. Electricity and magnetism, and the relationship between the two, are fundamental to the workings of the modern world.Key words: alternating current, amperes, atoms, attract, charge, circuit, conductor, direct current, electric current, electricity, electromagnet, electromagnetism, electrons, generator, hydroelectric plant, insulator, ion, lines of force, magnetic field, magnetism, neutrons, north pole, nuclear power plant, nucleus, permanent magnet, power plant, protons, repel, resistance, shock, solar power plant, south pole, static electricity, temporary magnet, transformer, transmission lines, turbine, volts, watts

    Key comprehension skills: Identify facts Other suitable comprehension skills: Compare and contrast; classify information; cause and effect; elements of a genre; interpret graphs, charts, and diagrams; using a glossary and boldfaced terms; using a table of contents and headings

    Key reading strategy: Ask and answer questions Other suitable reading strategies: Connect to prior knowledge; summarize; visualize; retell

    Photo Credits: Front cover: iStockphoto.com/Giles Angel; back cover: Ron Giling/PhotoLibrary; title page: Dannyphoto80/Dreamstime.com; page 3: iStockphoto.com/Mark Stay; page 4: Jupiterimages Corporation; page 9 (top): iStockphoto.com/Clint Spencer; page 9 (bottom): Image Source/Corbis; page 10 (top left): iStockphoto.com/Vinicius Ramalho Tupinamba; page 10 (bottom left): iStockphoto.com/John Scott; page 10 (right): iStockphoto.com/ Yunus Arakon; page 11: GIPhotoStock/Photo Researchers, Inc.; page 12 (left): iStockphoto.com/Viacheslav Krisanov; page 12 (right): iStockphoto.com/Pixhook; page 13 (left): iStockphoto.com/DSGpro; page 13 (center left): iStockphoto.com/ Nasen Mann; page 13 (center right): iStockphoto.com/Hywit Dimyadi; page 13 (right): iStockphoto.com/Gordon Dixon; page 15 (top): 3desc/Dreamstime.com; page 15 (bottom): iStockphoto.com/Matthew Cole; page 16: Michael Newman/PhotoEdit; page 17: Mary Evans Picture Library; page 18: iStockphoto.com/Billy Gadbury; page 19: iStockphoto.com/Leif Norman; page 20 (top): Aschwin Prein/Dreamstime.com; page 20 (bottom): Learning AZ/Doug Tepper; page 21 (left): iStockphoto.com/ Ekspansio; page 21 (right): iStockphoto.com/Robert Dupuis; page 22: Eric Brow/ Dreamstime.com

    illustration Credit: Pages 57,14: Learning AZ

    Electricity and Magnetism Learning AZ Written by David Dreier

    All rights reserved.

    www.sciencea-z.com

    Electricity and Magnetism

  • 3 4

    Introduction

    Have you ever looked out a window at night and watched flashes of lightning split the night sky during a raging thunderstorm? You might be surprised to know that lightning is a natural form of electricity. In the last two hundred years, people have learned how to produce and harness electricity. Whenever you flip a switch to turn on a light, you are using electricity. Computers and televisions cant work without electricity. Electricity has become such an important part of our everyday lives that it is difficult to imagine the world without it.

    Magnetism is also a familiar part of our world. Perhaps you have played with magnets or use magnets on your refrigerator door. Did you know that magnetism is closely related to electricity? This book will teach you about electricity and magnetism, as well as how they are related.

    Table of Contents

    Introduction .............................................................. 4

    What Is Electricity? .................................................. 5

    The Two Kinds of Electricity .................................. 8Static Electricity ...................................................... 8 Electric Current .................................................... 10

    Measuring Electricity ............................................. 13

    What Produces Magnetism? ................................. 14

    Magnetism and Electric Currents ........................ 16

    Producing Electricity ............................................. 17Steam ..................................................................... 19 Water ..................................................................... 19 Wind ...................................................................... 20

    Delivering Electricity ............................................. 21

    Electricity and Magnetism in Todays World ............................................... 22

    Glossary ................................................................... 23

    Index ........................................................................ 24

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    5 6

    What Is Electricity?

    You just learned that electricity can be produced naturally or by people. But what is electricity? It is a form of energy. Electrical energy comes from tiny, invisible particles called atoms. Atoms are the smallest bits of elements, the basic substances that make up all matter. Inside each atom are even smaller particles called protons, neutrons, and electrons.

    Protons and neutrons make up an atoms center, called the nucleus. Protons have a positive charge, while neutrons are neutral, meaning they have no charge. Electrons have a negative charge. Charges of the same kindsuch as two positive chargesrepel each other. Charges that are oppositea positive and a negative charge attract each other. PARTICLES HAVE CHARGES

    In diagrams, protons have a + sign on them, and electrons have a sign on them to show their charges. Neutrons have no label because they have no charge. This carbon atom has six electrons, six neutrons and six protons.

    Electrons quickly orbit, or move in a circle around, an atoms nucleus.

    Because electrons and protons are drawn to one another, you might wonder why electrons dont get pulled into the nucleus of an atom. They dont because electrons whirl around the nucleus very quickly. Their high speed keeps them from crashing into it.

    Normally, the number of positive protons and negative electrons in an atom is equal. Because the number of positive charges is equal to the number of negative charges, they cancel each other out. The atom is neutral, meaning it has no charge.

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    electron

    electron

    proton

    proton

    neutron

    neutron

    ELECTRONS CIRCLE THE NUCLEUS

  • 8

    The Two Kinds of Electricity

    There are two kinds of electricity: static electricity and electric currents. They both involve the production and movement of charges. But they behave in very different ways.

    Static Electricity

    Static electricity is caused by a buildup of negative charges in one place and positive charges in another. When the attraction between the positive and negative charges becomes strong enough, the particles quickly stream back together.

    Lightning is the most dramatic example of static electricity. In storm clouds, strong winds cause icy particles to collide violently. These collisions strip away many of the particles outer electrons, leaving the cloud full of positive ions and free electrons. The positive ions move to the top of the cloud. The electrons, which have a negative charge, collect at the base of the cloud. When the collections of positive and negative charges get large enough, they rapidly flow back together. As they do, the energy of their motion heats the surrounding air and creates a lightning flash. A lightning bolt heats the air around it to about 30,000C (54,000F). Thats five times as hot as the surface of the Sun!

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    Atoms can gain or lose electrons by contacting other atoms. If an atom gains electrons, it acquires a negative charge because the electrons outnumber the protons. If an atom loses electrons, the protons outnumber the electrons, so the atom has a positive charge. An atom that has a charge is called an ion. An atom that has more electrons than protons is a negative ion. An atom with more protons than electrons is a positive ion.

    It is important to remember that charges do not exist by themselves. A charge is always connected to a particle. Negative charges are carried by either electrons or negatively charged ions. Positive charges are carried by protons or positively charged ions.

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    Positive Ion

    Negative Ion

    Positive ions have more protons than electrons.

    Negative ions have more electrons than protons.

    electron

    proton

    neutron

    POSITIVE AND NEGATIVE IONS

  • Sometimes the ground and the clouds have strong opposite charges. When this happens, an electrical charge flows between the cloud and the ground. This charge creates the lightning bolts that strike buildings and trees.

    You can make a mini lightning bolt by scuffing your shoes on a carpet when the air is dry. Your body will pick up electrons from the carpet, gaining negative charge. If you put your finger near an object that has a neutral or positive charge, a spark will jump from your finger.

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    Lightning that strikes the