I learned electronics as a kid from a kit that used a water analogy to describe things. The transistor was described as a vane across a large water canal, conne

I learned electronics as a kid from a kit that used a water analogy to describe things. The transistor was described as a vane across a large water canal, connected with a hinge to a smaller vane in a smaller water canal, which allowed it to move up and down. So, a small water current in the small canal could cause a large water current in th large canal. Did it fully and accurately describe the gain characteristics of a real transistor ? No, it didnt. But it would be ridiculous to dismiss it entirely as a learning tool because of it. Overall I think the hydraulic analogy is a very good one, it holds up well and it breaks down only in the face of quantum phenomenon. It allows to understand electricity using concepts children are familiar with. All children like to play with water and have some intuitive sense of it. By the time you care about quantum electronics you can also understand the limitations of the analogy.