Why won the saltwater in our project conduct electricity?
Salt water doesn’t conduct as well as a copper wire. You can get better conduction by increasing the surface area of your submerged electrodes and decreasing the distance between them. Your alarm requires a certain minimum current. You can increase the current by increasing the voltage. To get 1.5 volts across the alarm, you might need to have 6 volts across the water; so that would require five 1.5 volt cells. Most water detector circuits use an amplifier. A few milliamps of current thru the water will turn on a transistor which permits a much larger current thru the alarm. Such a circuit can detect even tap water because of the tiny amount of dissolved electrolytes, but it cannot detect distilled or demineralized water.
