- 1). Establish a reference point, or ground. All potential energy needs a reference point. A mass suspended above the earth has potential energy measured with respect to its distance from the earth's surface, which is its reference point. For electric potential, the most common choice for reference, or "ground," is the earth, but the negative end of a battery will also suffice.
- 2). Define a component to assess for your calculation. For example, pick an off-the-shelf battery, or build a homemade galvanic cell as a battery. You will measure electric potential (per unit charge), or voltage, at your battery's positive terminal with respect to its negative terminal.
- 3). Place an ammeter and a resistor of known resistance, measured in ohms, together in series across your battery's terminals. Visit an electronic shop like Radio Shack and pick up a battery holder with wires that you can twist around resistor leads.
- 4). Turn on the ammeter and read the current flowing through it.
- 5). Turn off the ammeter and calculate potential from Ohm's Law, which dictates that voltage = current * resistance. For example, if you read 15 milliamps through your ammeter and the resistor has a value of 100 ohms, your battery's electric potential (per unit charge), or voltage, equals 1.5 volts, which is the nominal voltage of a AAA or AA battery.
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