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poison_tastes_good
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Hello. I have a dilemma with a DC circuit containing a motor. The motor has a load attached, and i am varying power to the motor. I have a voltmeter connected across the motor in parrallel, and an ammeter connected in series to the wire, as i should. I expected that as i raised the power, voltage and current would increase, as P=IV. My load is constant and i make no changes to the motor, so I expected resistance to stay the same. However, i found that as the motor began to move, my current remained at 0.5A, but my voltage increased, violating V=IR. Either resistance is changing in a way i can't understand, or current is icreaseing but my ammeter is not picking up on this for some reason. Two theories i came up with are: 1-I thought maybe 0.5A was a sort of threshold for movement, and after that all of the extra current would be transferrend into movement energy and so the ammeter is only measuring the remaining current in the wire and not taking into account the current transferred to movement energy. 2-But perhaps as the load begins to move, it's resistance increases. I just want to know which theory would be right, if any. Cheers. John, A level student, 2nd year.