DIRECT AND ALTERNATING CURRENTS

№ 15. BATTERY

The battery is a means of storing current, it is the most important part of the electrical equipment. The output of the generator and the demands for electrical energy are very variable. Therefore a reservoir of electrical energy is required. This reservoir is the battery. The battery requires a fortnightly addition of distilled water up to the bottom of the filler tubes. Water for a battery must be kept in clean covered vessels of glass, china, rubber or lead. There are three fillers in a six-volt battery and each must receive individual attention. When replacing the battery in the car, be sure to install it with the positive terminal grounded to the frame.

№ 16. DIRECT AND ALTERNATING CURRENTS

The current which moves steadily in one direction we call a direct current. A direct current is, of course, useful. We know that the electrical system in an automobile and an airplane uses direct current. The telegraph, the telephone and the tram use the direct current too. Direct current is also used to meet some of the industrial requirements. The current flowing first in one direction and then in another we call an alternating current. In spite of its usefulness a direct current system has one great disadvantage. There is no easy economical way to decrease or increase its voltage. The alternating current does not know this disadvantage. Alternating voltage increases or decreases with little energy loss owing to the transformer. The alternating current supplies the greatest part of the electric power for industry today. At present most cities use an alternating current for lighting, heating and other purposes.

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