Ohm's Law

Ohm's law is a mathematical relationship of three variables in an electronic circuit containing a resistive element. It states that the voltage across a resistive element is equal to the current passing through the resistive element times the resistance of the resistive element.

In mathematical terms, this is written as:

<math>V = I*R</math>

Where

V: Voltage across resistive element

I: Current through resistive element

R: Resistance of resistive element

In this equation, R is always constant, regardless of the current and voltage. In real life, however, the temperature of a resistor will rise as the current through it increases. Since resistance and temperature are positively correlated, Ohm's law becomes only an approximation (and sometimes a very bad approximation) when the resistive element heats up. For example, an incandescent light bulb does not follow Ohm's law because it becomes hot very rapidly when a current is applied.