Measuring moving charges. Voltmeter. Measures potential difference (voltage), the energy of each charge Connects to either side of a load. Ammeter. Measures current, how many charges move past a point in a given time. Connected into a circuit between two parts. Ohm’s Law.
V = IR
V - voltage (measured in volts, V)
I - current (measured in amps, A)
R - resistance (measured in ohms, Ω)
120 V = R
Therefore the resistance of the can opener is 80 Ω.