Ohm's law

Ohm's law states that the current through a resistor is inversely proportional to the potential difference or voltage across the resistor. The mathematical equation that describes this relationship is V=IR

where I is the current in amperes (often shortened to "amps"), V is the potential difference in volts, and R is the resistance (measured in ohms). The potential difference is also known as the voltage drop, and is sometimes denoted by U, E or emf (electromotive force) instead of V.