Hi there, I have been trying to determine the resistance for a variety of wires in the prep room. I use the simple circuit with the power supply the ammeter and the voltmeter. I put crocodile clips at the edges of the wire and I have results for all of them but the copper. When I connect the coper wire to the circuit the ammeter and the voltmeter just become crazy, the voltmeter doesn't even show the voltage I apply with the power supply, imagine that it shows one decimal lower. What's going on with the copper wire?