- Location
- Connecticut

- Occupation
- Engineer

Originally Posted bydavid luchini

You are not following Ohm's law in this case. Ohm's law says "the current through a conductor between two points is directly proportional to the potential difference or voltage across the two points, and inversely proportional to the resistance between them. You have clearly stated that there is no potential source in your circuit, therefore there is no potential difference and therefore no current. The current is zero.

Mivey, again you are missing the point - there seems be quite a bit of that going around. My post above was a response to crossman gary's post #167. He asked in post #167, if you take a zero impedance conductor and close it into a loop with no potential source included, "What does math and Ohm's Law predict about the current flow? E = I x R, 0 = I x 0, What is I?"No, it will show that it takes zero voltage for a current to flow through a zero resistance. Not that the current has to be zero.

You can use Ohm's law to predict the voltage drop across two points in a circuit (V=IR) if you know the current and resistance across the two points, or to predict the current if you know the voltage drop and resistance (I=V/R) or to predict the resistance if you know the voltage drop and current across the two points (R=V/I.)

You responded that Ohm's Law "will show that it takes zero voltage for a current to flow through a zero resistance. Not that the current has to be zero." You are misapplying Ohm's law the same way crossman gary did.

Crossman gary described an "inactive" circuit. He created a loop of wire with no potential source added. In his circuit, there is no potential source, and therefore, no current flowing in the circuit. The must be an "active" source in the circuit to create current flow. My point to crossman gary was that Ohm's law CANNOT be applied to the circuit he described. The circuit resistance in the example is a known and constant value (0 Ohms,) but two predict the voltage drop between two points you must know what the current is between those two points, and to predict the current flow between two points you must know what the voltage drop between the two points.

Since the circuit in question is an "inactive" circuit, we already know that the voltage drop between any two points wil be zero, and that the current flow between any two points will be zero. I suppose that we could mathematically apply Ohm's law as 0=0x0, but what is the point. Since the purpose of Ohm's law is predict voltage drop, or current, or resistance between two points in a circuit, I would suggest that it should only be applied to "active" circuits.