For example, many people imagine that, when they plug their vacuum cleaners and blenders into outlets in the wall, the electricity flows like water from the wall to the appliances through the little black tube of the electrical cord.

• 比如，很多人想像当他们将真空吸尘器或者搅拌机接到墙上的电源插座时，电流会像水一样通过黑色的小电线管从墙里流向电器。