Electric Power is generated by converting heat, light, chemical energy, or mechanical energy to electrical energy. Most electrical energy is produced in large power stations by the conversion of mechanical energy or heat. The mechanical energy of falling water is used to drive turbine generators in hydroelectric stations, and the heat derived by burning coal, oil, or other fossil fuels is used to operate steam turbines or internal-combustion engines that drive electric generators. Also, the heat from the fissioning of uranium or plutonium is used to generate steam for turbine generator in a nuclear power plant.
Electricity generated by the conversion of light or chemical energy is used mainly for portable power sources. For example, a photoelectric cell converts the energy from light to electrical energy for operating the exposure meter in a camera, and a lead-acid battery converts chemical energy to electrical energy for starting an automobile engine.
Electric power produced in large power stations generally is transmitted by using an alternating current that reverses direction 25, 50, or 60 times per second. The basic unit for measuring electric power is the watt – the rate at which work is being done in an electric circuit in which the current is one ampere and the electromotive force is one volt.
Electric energy consumption normally is given in kilowatt-hours – that is, the number of kilowatts used times the number of hours of use. Electricity is clean, inexpensive, and easily transmitted over long distances. Since the 1880’s, electricity has had an ever-increasing role in improving the standard of living. Now it is used to operate lights, pumps, elevators, power tools, furnaces, refrigerators, air-conditioners, radios, television sets, industrial machinery, and many other kinds of equipment.
II. Read the text B and list the most important inventions in the field of electrical engineering. Translate.
Electricity
It is impossible to imagine our civilization without electricity: economic and social progress will be turned to the past and our daily lives completely transformed. Electrical power has become universal. Thousands of applications of electricity such as lighting, electrochemistry and electrometallurgy are longstanding and unquestionable.
With the appearance of the electrical motor, power cables re¬placed transmission shafts, gear wheels, belts and pulleys1 in the 19-th century workshops. And in the home a whole range of various time and labour saving appliances2 have become a part of our everyday lives. Other devices are based on specific properties of electricity: electrostatics in the case of photocopying machine and electromagnetism in the case of radar and television. These applications have made electricity most widely used.
The first industrial application was in the silver workshops in Paris. The generator — a new compact source of electricity — was also developed there. The generator replaced the batteries and other devices that had been used before.
Electric lighting came into wide use at the end of the last century with the development of the electric lamp by Thomas Edison. Then the transformer was invented, the first electric lines and networks were set up, dynamos and induction motors3 were designed. Since the beginning of the 20th century the successful develop¬ment of electricity has begun throughout the industrial world. The consumption of electricity has doubled every ten years.
Today consumption of electricity per capita4 is an indicator of the state of development and economic health of a nation. Electricity has replaced other sources of energy as it has been realized that it offers improved service and reduced cost.
One of the greatest advantages of electricity is that it is clean, easily-regulated and generates no by-products5. Applications of electricity now cover all fields of human activity from house washing machines to the latest laser devices. Electricity is the efficient source of some of the most recent technological advances such as the laser and electron beams. Truly6 electricity provides mankind with the energy of the future.