. Electricity in diseases of the eye, ear, nose and throat . ceof one ohm. The electro-motive force produced byone Daniell cell is volts. An ohm may be represented by the resistance ofa copper wire, two hundred and fifty feet long andone twentieth of an inch in diameter. The amperageis not the rate of flow or quantity or volume of thecurrent, as is frequently stated. It may be definedas the amount of energy which the magnetic field ofthe current shows in attracting a needle. The amount, volume, quantity or rate of flow ofthe current is represented by the amperage multi-plied by the time:
. Electricity in diseases of the eye, ear, nose and throat . ceof one ohm. The electro-motive force produced byone Daniell cell is volts. An ohm may be represented by the resistance ofa copper wire, two hundred and fifty feet long andone twentieth of an inch in diameter. The amperageis not the rate of flow or quantity or volume of thecurrent, as is frequently stated. It may be definedas the amount of energy which the magnetic field ofthe current shows in attracting a needle. The amount, volume, quantity or rate of flow ofthe current is represented by the amperage multi-plied by the time: that is—one ampere, multipliedby one second, equals one coulomb. Difference of Potential.—If a different poten-tial or voltage be applied to each end of aconductor, as to the prime conductors of a coil, thedirection of the current will be towards the lesser 18 PHYSICS OF ELECTRICITY. potential and its energy will be the difference be-tween the potentials. Figaire 14 may illustrate this. Let the pressureof the water in the tube, between A. and B. be 100. Pig. 14. and between C. and B. be 30, the flow will be 70 andfrom C. The law which governs these three factors iscalled Ohms Law, and is as follows: The electro-motive force divided by the resistance is equal to thecurrent or intensity; or, using the units of these fac-tors, one volt divided by one ohm equals one is, the current varies directly as does the vol-tage and inversely as does the resistance. Or, in oth-er words, the resistance remaining constant, the cur-rent increases or diminishes, as the voltage in-creases or diminishes: or again, with the voltage re-maining the same, the current is increased by dimin-ishing the resistance or decreased by increasing theresistance. THE DIRECT CURRENT. 19 Having- the volts and tlie ohms, the amperes areestmiated by dividing the volts by the ohms. Hav-ing the volts and the amperes, the ohms may be de-termined by dividing the volts by the the ohms and the
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