Voltage is measured by means of a potentiometer (it does, one must admit, sound like a poorly accomplished sex joke from start to finish). The strength of voltage gives us a good sense of the work that electrons can reliably be asked to do as they bump their way through the system and pass through our stuff. One hundred ten volts can power a bulb, 220 an electric razor, 500 a streetcar, and 2,000 an electric chair; 50,000 volts is good for high-voltage transmission lines and 100,000 volts for a stun gun.
