I would like to measure the resistance of a resistor in the most basic way by running a current through it and measuring current and voltage. I understand that I have basically two options to place voltmeter and ammeter:
- If I measure the voltage over the ammeter+resistor, I get an error due to the non-zero resistance/voltage drop over the ammeter. So basically the voltage I measure is not the voltage over the resistor but somewhat larger. The measured current is correct though. This method should work well if the measured resistor has a much larger resistance than the ammeter.
- If I measure the voltage over the resistor, the measured voltage will be correct, however now the measured current will be larger than the current through the resistor. I understand that if the resistor has a much smaller resistance than the voltmeter this error should be negligible. This method should work well for measuring small resistances.
I have two questions:
- If the resistor to be measured has a resistance value that lies in-between those of voltmeter and ammeter, how do I decide which method to use?
- If a series resistor (of known resistance) is used, how would I set up volt/ammeter?
Please keep the answer simple as I am not an electrical engineer.