Can salt water conduct enough electricity to light a bulb while distilled water cannot? You set up two beakers with copper electrodes -- one filled with distilled water and one with sea water. A battery, a light bulb, and an ammeter complete the circuit. You measure the voltage, current, and bulb brightness for each solution. The voltage stays nearly the same in both beakers. The current, however, jumps from almost zero in distilled water to a level that lights the bulb in sea water. The difference comes from dissolved salt ions that carry charge through the liquid.