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The resistance of any electrical device is defined by the expression, R=V/I, where V (volts) is the potential difference across the device and I (amps) is the electrical current flowing through it.

When a current of one amp flows through a resistor after a potential of one volt is placed across it we say that the resistor has a unit resistance of one ohm. If the resistor is a metallic conductor then, as long as it's **temperature** is constant it's resistance remains constant. In other words, the ratio of potential difference (V) and current flow (I) remains constant. This is **Ohm's Law**. This means that for any given resistor doubling the potential potential across its ends will double the current flowing through it, tripling the potential will triple the current, etc.

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This section contains 640 words(approx. 3 pages at 300 words per page) |