- #1
bluey107
- 1
- 0
Hey all, I have a small question that's been bugging me and I can't find an answer anywhere. How do you test the resistance of a DC motor?
My main "practical" idea is to test it as you'd test any other piece of metal: connect a power supply, an ammeter and a dc motor in series, and connect a voltmeter to measure the potential difference across the motor (in parallel), then take all the readings and calculate using the R=V/I formula.
However, I thought maybe it has something to do with back emf/induced current? In this case, would I connect a galvanometer instead of an ammeter (same setup as above), start up the motor, record the reading, then hold down the motor to see the supply current, and then measure the induced current? But then, would I use the induced current, the supply current or the net current in the R=V/I calculations?
My third thought is very vague, and I have almost no backing for it, but would there be any way to measure the back emf? Because isn't that kind of the resistance of a motor?
Please help, we were just given the aim of this experiment in class and told to figure out the rest if we wanted a head start for a practical exam coming up.
My main "practical" idea is to test it as you'd test any other piece of metal: connect a power supply, an ammeter and a dc motor in series, and connect a voltmeter to measure the potential difference across the motor (in parallel), then take all the readings and calculate using the R=V/I formula.
However, I thought maybe it has something to do with back emf/induced current? In this case, would I connect a galvanometer instead of an ammeter (same setup as above), start up the motor, record the reading, then hold down the motor to see the supply current, and then measure the induced current? But then, would I use the induced current, the supply current or the net current in the R=V/I calculations?
My third thought is very vague, and I have almost no backing for it, but would there be any way to measure the back emf? Because isn't that kind of the resistance of a motor?
Please help, we were just given the aim of this experiment in class and told to figure out the rest if we wanted a head start for a practical exam coming up.