A laboratory manual in physics, to accompany Black and Davis' "Practical physics for secondary schools," (1913)
Black, Newton Henry, 1874- [from old catalog] · New York, The Macmillan company · leaf 95
EXPERIMENT 38 EFFICIENCY OF AN ELECTRIC MOTOR What is the ratio of the mechanical output of an electric motorto the electrical input ? 0.25 horse power motor.110-volt direct currentline or storage battery.Ammeter.Voltmeter. Two spring balances and sup-port.Cord or strap for brake.Speed… … Fig. 48 tensity of the current /and put a voltmeter across the brushes(Fig. 48) to get the electrical pressure E. From these two factors we may eas-ily compute the inputin watts which isequal to the productof volts times am-peres. To get the mechanical output we may make a brake test.A very simple…
Physics
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