Introduction. Lamplighters It was a lamplighter s job to light the gas streetlights.

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2 Introduction Do you need some light so that you can read? Flip a switch. Would you like a piece of toast? Drop a slice of bread into the toaster. Do you want to know what s going on in the world? Turn on a TV news program. What do these events have in common? They all use electricity. It is hard to imagine life without electricity. Yet, not long ago, things were very different. Streetlights used gas and had to be lit with a spark or a match. In fact, it was someone s job to light them at night! Lamplighters It was a lamplighter s job to light the gas streetlights. 2

3 It took hundreds of years to develop the electrical system we take for granted today. Let s start by looking back to times when electricity was not as available as it is today. You might hate to do laundry today, but doing laundry in the early 1900s used to be much more work. Washing and drying a load of laundry took hours. People washed clothes by hand. People used a wash tub, an agitator, a washboard, and a clothes wringer. They placed dirty clothes in a tub with soapy water. They used an agitator to mix around the clothes. Next they scrubbed the clothes using the washboard. Then they rinsed the clothes in clean water and ran the clothes through the wringer. This process had to be repeated many times. When the clothes were clean, people hung the clothes outside to dry. Making clothes was also hard work. People used foot pedals to power the sewing machines. Think about having to power the machine yourself while trying to feed the cloth under a sharp bobbing needle. Would you like to have a cold glass of milk? If so, you had better hope that the iceman brought a new block of ice for the icebox! Iceboxes kept food and beverages cool. A typical icebox held a 25-pound block of ice. This ice block would last for a few days. Iceboxes were common in homes as late as the 1940s. As you will soon learn, electricity and electric appliances started appearing in the home only about one hundred years ago. They changed the way people lived. 3

4 Electricity and Magnetism Discoveries The history of electricity is a long one. The people of ancient Greece knew that rubbing a piece of amber (hardened tree resin) would make feathers stick to it. Unknown to the Greeks, they had discovered static electricity. Magnets and magnetism were also not understood. By the early 1800s, scientists began thinking that electricity and magnetism might be related. In 1820, Hans Oersted, a scientist and instructor, was doing a demonstration for his students. In the demonstration, he noticed something strange happening to the needle of a nearby compass. The needle moved away from north when a current flowed through a wire that was close to it. The electric current had produced a magnetic field. This was proof that electricity and magnetism were related! Soon people started wrapping wires into coils. They had found that running a current through a coiled wire produced a greater magnetic field. This simple device is an electromagnet. Advances in electromagnetism continued to occur. Inventors and engineers began looking for ways to make useful electrical devices. In 1829, an American named Joseph Henry made one of the earliest useful electromagnets. He made an electromagnet capable of lifting hundreds of pounds. Within a few years, he found a use for his electromagnets in the mining industry. In 1833, an ironworks company in New York State began using Henry s electromagnets to separate crushed iron ore. Workers at the company moved 4

5 magnetized spikes through the ore. Ore with the highest iron content stuck to the spikes. This high-iron-content ore produced high-quality iron. Around the same time period, a scientist named Michael Faraday was studying electricity. He asked the question, If electricity can produce magnetism, can magnetism produce electricity? In 1831, he moved a magnet through a coil of wire. He found that this motion made a small electrical current in the wire. This process became known as induction. Faraday s discovery was a huge breakthrough. He had discovered how to generate electricity by movement in a magnetic field. By 1850, electromagnetic generators were being used in an electroplating factory. The electrical age had begun. Movement of Magnet Coil Magnet Meter shows that a current flows as the magnet moves. Michael Faraday discovers induction When the magnet and the coil move past each other, they produce an electric current. This process is called induction. 5

6 Putting the Discoveries To Use New discoveries about electricity and magnetism improved communication and people s understanding of medicine. In 1844, Samuel Morris changed the world of communication by building the first practical telegraph. The telegraph was the first far-reaching electromagnetic communication device. Before the telegraph, letters could take weeks or months to reach their destination. The telegraph made quick communication over long distances possible. The telegraph was a simple machine. Coded messages were tapped out on the sending end. These messages were recorded and decoded on the receiving end. Electricity also found its way into medicine. In the 1840s, French medical doctor Guillaume Duchenne used electricity to study muscle contraction and paralysis. Duchenne s work laid the groundwork for the field of neurology. Neurology is the study of the nervous system. Morse telegraph Messages sent by telegraph are tapped out in Morse code. Morse code is a series of dots and dashes. The signals could travel hundreds of miles. They were recorded on a strip of paper at the receiving end. Receiving Unit Paper Strip Penlike Device Sending Unit Electromagnet Power Source 6

7 Electric Motors In 1834, Thomas Davenport developed what were probably the first commercially successful electric motors. He used the motors to power a number of existing machines. One of these machines was a printing press. However, it would take almost 50 more years for electric motors to come into wide use. By the late 1800s, improvements in the electric motor made it more useful. In fact, during the Vienna World Exposition in 1873, electric motors were a hit! People realized that electric motors could do big jobs. Some of the first uses were in streetcars. Today, many streetcars around the world are still powered by electricity. An electric motor Current flows through the wire on the inside of magnets. The current produces a magnetic field around the wire. This causes the wire to spin. The spinning wire causes the shaft to spin. Wire Spins Current In + 7

8 Thomas Edison The late 1800s was also a time for huge advances in lighting. In 1879, Thomas Edison produced the first practical light bulb. Unlike earlier bulbs, his bulb did not burn out in just a few minutes. Light bulbs are not useful if people do not have electricity in their homes. So Edison set out to develop a complete electrical system. He would need to find a way to produce electricity and deliver it to homes. This was a huge task. But in 1882, Edison opened the world s first commercial electricity plant in New York City. It was called Pearl Street Station. Pearl Street Station was huge for its day. However, the plant had some limitations. It could only produce and deliver electricity to a small section of the city. Edison s plant did show that electrifying a city was possible. Further advances would soon bring electricity to much of the country. Thomas Edison s first practical light bulb 8

9 E Edison s plant produced direct current (DC) electricity. In a direct current, the current flows in one direction. Unfortunately, direct current does not transmit over long distances through wires very well. Today, electricity is delivered as an alternating current (AC). In an alternating current, the direction of the current switches back and forth. Alternating current transmits well over great distances. It is also easy to increase or decrease the voltage. In 1883, an AC motor was developed. The advantages of AC eventually led to its widespread use. Pearl Street Station Pearl Street Station was the first electrical energy plant in the United States. It provided electricity for one square mile of New York City. The map shows the area that Pearl Street Station supplied with electricity. R I V E R N L Y K T O O A S B R 9

10 Electrifying America How is electricity delivered to your home today? A plant produces electrical power. The voltage increases. The electricity travels over long distances. The voltage decreases before it enters your home. The illustration below shows how the system works. Devices called transformers increase and decrease the voltage. Transformers that increase the voltage are called step-up transformers. Transformers that decrease the voltage are called step-down transformers. Some step-up transformers are located in large substations. Some stepdown transformers are located on the power poles you may have seen on the street. There are many different types of electrical plants. Electrical plants harness energy from different resources and convert it into electrical energy. 12,000 Volts 240,000 Volts Power Plant Power Substation (Step-up Transformer) High-Voltage Transmission Lines 10

11 Hydroelectric plants harness the energy in falling water. Fossil fuel plants burn coal or natural gas to release energy. Nuclear power plants use the energy released during a nuclear reaction. In windy areas of the country, windmills capture the energy of the wind. These and many other sources are all part of America s power production and distribution system. Most of these electrical plants have something in common. They use the energy from different resources to spin a coil of wire inside a magnetic field. This causes a current in the wire to produce electricity. Modern power distibution Transformers are used to increase and decrease the voltage of the electricity at different points in the system. Notice the huge differences in voltage at different points. 240 Volts 8,000 Volts Power Pole Power Substation (Step-down Transformer) 11

12 Today s Power Sources The United States produces and consumes a huge amount of energy every year. Today, this energy comes from many different sources. This was not always the case. In 1800, burning wood was the source for most energy needs. The use of coal as a major energy source began around By about 1885, coal was the leading energy source. From 1951 to 1982, petroleum (oil) was the major energy source. Since then, coal has once again become the major source. Much of the energy consumed in the United States is used to generate electricity. In 2003, the United States generated over 3,800 billion kilowatt hours (kwh) of electricity. The circle graph below shows a breakdown of the energy sources used to generate our electricity. These energy sources provide the electricity for all of the appliances and technologies that you count on and use every day. Electric power production This circle graph shows the energy sources used to generate electricity from January to August % Nuclear 17.5%% Natural Gas 6.7% Hydroelectric 3.2%%Petroleum 2.7%%Other 49.9% Coal 12