. Practical electricity for beginners. Electrical pressure is called voltage or electromotiveforce, the first being taken from the name of a man, Volta,who did a great deal toward the devel-oping of electricity, and the secondmeaning the force that causes elec-tricity to move. If only low pressuresand comparatively small quantities ofcurrent are required such as in the caseof ringing door bells and the like, drycells are used. Then, where greaterquantities of electricity are needed,storage batteries may well fulfill therequirements (Fig. 6). If, however,high voltages and large quantities arere
. Practical electricity for beginners. Electrical pressure is called voltage or electromotiveforce, the first being taken from the name of a man, Volta,who did a great deal toward the devel-oping of electricity, and the secondmeaning the force that causes elec-tricity to move. If only low pressuresand comparatively small quantities ofcurrent are required such as in the caseof ringing door bells and the like, drycells are used. Then, where greaterquantities of electricity are needed,storage batteries may well fulfill therequirements (Fig. 6). If, however,high voltages and large quantities arerequired, a small power plant must beinstalled or the power must be pur-chased from a central power station. 11. Brief Description of the DryCell.âSince the dry cell is one of themost common sources of small electrical pressures, it is wellto study it briefly at this time. Over one hundred years ago an experimenter namedVolta discovered that an electric current could be causedto flow by the use of chemicals. He found that when dilute. Fig. 6. Two of thecommon methods ofsupplying electricalpressuresâthe dry celland the storage battery. ELECTRICAL PRESSURES 21 sulphuric acid was placed in a glass tumbler and a strip ofzinc and a strip of copper suspended in it, an electric currentwould flow from the copper to the zinc if they were connectedby a conductor. The dry cell of today is the result of this discovery. Thezinc is made in the form of a can for thepurpose of retaining the rest of the cell,thereby doing away with the necessity ofusing a glass tumbler, the copper has beenreplaced by a carbon stick having thesame effect, and the sulphuric acid hasbeen replaced by other chemicals in theform of a paste instead of a liquid (Fig. 7). 12. Operation and Uses of Dry a cell is in use, the chemicals init eat the zinc and both chemicals andzinc are gradually used up. After thesehave been consumed, the cell is of no moreuse and is usually thrown away. Some- ge^on of a^d^ ti
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectelectri, bookyear1921
