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Electricity and Magnetism

Electricity is a class of phenomena arising from the existence of charge. According to the modern theory, most elementary particles of matter possess charge, either positive or negative. The basic unit of charge is that on the proton or electron — the proton's charge is designated as positive while the electron's is negative. Two particles with like charges, both positive or both negative, repel each other, while two particles with unlike charges are attracted.

There are two basic aspects of charge study. Electrostatic is the study of the charges, or charged bodies at rest. When positive or negative charge builds up in fixed position on objects, certain phenomena can be observed that are referred to as static electricity. Electrodynamics is the study of charges in motion. A flow of electrically charged particles constitutes an electric current.

It has been known for centuries that certain black, heavy stones have the property of attracting iron, this property be­ing called magnetism. A body that exhibits magnetism is called a magnet. The two parts of a magnet that show the strongest magnetism are called the North pole and the South pole.

Magnets not only affect ordinary iron, but they affect one another. When a pole of one magnet is brought toward a pole of the second magnet, they will repel if both are north poles or both are south poles, but they will attract if one is a north pole and the other a south pole.

The region in which magnetic forces act is called a mag­netic field.

When placed in a strong magnetic field, iron becomes magnetized.

Electricity and magnetism are closely connected. Almost all metals are good conductors of electricity, and copper is one of the best conductors of all. Glass, paper, rubber are the most common non-conductors or insulators.

Many practical applications have resulted from the utilisation of the magnetic effect of an electric current.

These effects are used in motors, in most electric meters (ammeters, voltmeters and galvanometers), in electromagnets and in practically all electromechanical apparatus.

Active vocabulary

to possess to designate matter to repel to attract collectively to refer to to build up arise

iron stone copper rubber property to constitute to exhibit utilisation application

Translate the sentences into Russian using dictionaries.

1) Two magnets put into a coil produce a greater effect than one.

2) The magnetic poles will repel if both are North poles or both are South poles.

3) Both glass and rubber are insulators.

4) There are instruments measuring current and voltage, and devices for measuring energy.

5) Iron becomes magnetized when it is placed in a strong magnetic field.

6) When the magnetic field is removed magnetization disappears.

7) Whenever a current is flowing in a circuit, it is due to the existence of an electromotive force in the circuit.

Give one word of the definition.

1. The flow of electricity along a wire.

2. The path of an electric current.

3. A reddish metal which conducts electricity and heat well.

4. Electric flow in one direction

5. Electric flow first in one direction and then in the other direction.

6. An instrument for measuring electric current.

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