# Ohm’s Law

Ohm’s Law is an essential law of electronics. It allows us to design and build electronic circuits without risk of harm to ourselves or to the components in our projects.

Ohm’s Law describes the relationship between the current (I), voltage (V), and the resistance (R) in a circuit, where the resistance can be understood to be the work to be done by the circuit. For example: if a waterwheel represents the resistance (or work) of a circuit, and the voltage represents the speed of the water, then current would be the amount of water that flows through the waterwheel. If the wheel is too small or the flow of water too fast, then too much water would flow unimpeded over the wheel.

The current *I* is measured in amps. Voltage *V* is measured in volts. Resistance *R* (also known as *impedance*) is measured in ohms (Ω).