English to Portuguese Tech/Engineering Electronics / Elect Eng electricity - online course

Não estou bem certa de que a tradução de bucket aqui é balde mesmo por causa da torneira.
In order to explain how electricity can transfer energy we will use an analogy with water. An electrical system, as an energy carrier, can be compared to a bucket filled with water, equipped with a tap and a drain pipe at the bottom of the bucket. As long as the tap is closed, the water droplets in the bucket move at random. When the tap is opened, the water flows out of the bucket, through the drain pipe, because of gravity and the height difference. A similar principle applies to the flow of electrons. As long as there is no source of electrical power, the electrons in the conductors also move at random. As soon as the conductors are connected to a positively charged and a negatively charged point, the flow of electrons is no longer erratic and will move in one direction through the conductor. The difference in charge is called the "potential difference" or the "voltage".