The positive lead is hooked up to one end of the material and the negative lead to the opposite end of the material. The power supply is set to 'Constant Voltage' but no matter how I adjust the voltage, the current continues to read zero. Does this system need to be grounded? However, the material is expected to have a moderate to high resistance; won't the electrical current simply flow to the ground, i.e. path of least resistance, if I hook it up that way?
Any insight on what I'm doing wrong would be greatly appreciated.
Current is zero means the circuit you have connected is open(have many reason 1.wire or lead you used may broken internally,2.You may confused in second ground or negative terminal etc.) or if the current setting on your power supply may at minimum, hence connect ammeter, between D.C power supply terminals via rheostate, and find first current is flowing or not, then connect the material......
Bhupendra Desai, thank you for your response. I still need to do a bit more testing to be sure but I think that the material was such a strong insulator that the ammeter built in to the DC supply unit didn't have high enough resolution to measure it. I tested just a lightbulb in my setup and it worked perfectly. The voltage and current measurements come out to the expected resistance of a 120 V bulb so I think the problem was the material we were measuring itself. But I appreciate your suggestions and will certainly check all the cables. For a DC power supply I've read that ground and negative are the same thing. Is this true?
No, negative and ground are not same, ground is a reference terminal with zero(ground) potential, positive at higher potential and negative at lower potential. If negative is taken as reference ground(+5v and -5V supply ), positive would shift to +10V with respect to ground. For example, in A.C the polarity of phase is changing positive and negative with respect to neutral/ground (zero potential) 60 times in second(60Hz).
In order to verify the integrity of your setup, why don't you first take up a sample with known (pre-determined) results. If it still shows zero there could be a possible flaw in the system itself.
Perhaps someone could explain when a ground is necessary then? I understand that the main/general application is of course safety, however I know that in some cases it's necessary to have the ground as zero for a reference point. If the material that I'm testing is that highly resistive though, why wouldn't the current flow to the ground instead?
Power supply, would considered, like source(battery), supplying power where current flow from positive to negative via load, and circuit completed internally by flow from negative to positive. Body of power supply is ground/earth for safety from humming, or leakage, it is not coming in circuit, hence current would not flow......
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