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WHAT IS ELECTRICITY?
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WHAT IS ELECTRICITY?

       Electricity is a form of energy involving the flow of electrons. All matter is made up of atoms, and an atom has a center, called a nucleus. The nucleus contains positively charged particles called protons and uncharged particles called neutrons. The nucleus of an atom is surrounded by negatively charged particles called electrons. The negative charge of an electron is equal to the positive charge of a proton, and the number of electrons in an atom is usually equal to the number of protons. When the balancing force between protons and electrons is upset by an outside force, an atom may gain or loose an electron. When electrons are "lost" from an atom, the free movement of this electron constitutes an electric current.

     Electricity is a basic part of nature and it is one of our most widely used forms of energy. We get electricity, which is a secondary energy source, from the conversion or other sources of energy, like coal, natural gas, oil, nuclear power and other natural sources, which are called primary sources. Many cities and towns were built alongside waterfalls (a primary source of mechanical energy) that turned water wheels to perform work. Before electricity generation began slightly over 100 years ago, houses were lit with kerosene lamps, food was cooled in iceboxes, and rooms were warmed by wood-burning or coal-burning _stoves. Beginning with Benjamin Franklin's experiment with a kite one stormy night in Philadelphia, the principles of electricity gradually became understood. In the mid-1800s everyone's life changed with the invention of the electric light bulb. Prior to 1879 electricity had been used in arc lights for outdoor lighting. The 1ightbulb's invention used electricity to bring indoor lighting to our homes.

     An electric generator (Long ago a machine that generated electricity was named "dynamo", today's preferred term is "generator".) is a device for converting mechanical energy into electric energy. The process is based on the relationship between magnetism and electricity. When a wire or any other electrically conductive material moves across a magnetic field, an electric current occurs in the wire. The large generators used by the electric utility industry have a stationary conductor. A magnet attached to the end of a rotating shaft is positioned inside a stationary conducting ring that is wrapped with a long, continuous piece of wire. When the magnet rotates, it induces a small electric current in each section of wire as it passes. Each section of wire constitutes a small, separate electric conductor. All the small currents of individual sections add up to one current of considerable size. This current is what is used for electric power.

     An electric utility _ power station uses either a turbine, engine, water wheel, or other similar machine to drive an electric generator or a device that converts mechanical or chemical energy to electricity. Steam turbines, internal-combustion engines, gas combustion turbines, water turbines, and wind turbines are the most common methods to generate electricity.(2584 знаків)

1 Say which statements are true or false. If they are false correct them.

  1 The nucleus of an atom is surrounded by negatively charged particles called protons.

  2 When the balancing force between protons and electrons is upset by an outside force, an atom may gain or loose an electron.

  3 We get electricity from the conversion of primary sources.

  4 When a wire or any other electrically conductive material moves across a magnetic field, an electric current occurs in the wire.

  5 An electric utility power station uses either a turbine, engine, water wheel, or other similar machine to drive an electric generator or a device that converts mechanical or chemical energy to electricity.

 2 Answer the following questions:

  1 What does the term  e l e c t  r i c i t y  mean?

  2 What constitutes an electric current?

  3 How did people leave before electricity generation?

  4 What is an electric generator? How was it named long ago?

  5 What are the most common methods to generate electricity?



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