Author Options:

Voltage: In search of a better analogy than water Answered

I need to come up with a good analogy to describe the concept of Voltage. Water seems to be the most common analogy, but it seems to fail in some way. Here is a good water analogy that I found, but it still leaves questions that I cannot answer.

The Lake Analogy:
No force is pushing or pulling on the water inside a lake, so nothing moves. If it were possible to lift up on one side of the lake and tip it at an angle, gravity would pull on the water and it would flow. We have created a gravitational potential difference. The side that we lifted up on now has a higher potential than the lower side. Gravity will always cause water to flow from the point of highest potential to the point of lowest potential. The higher the difference between these two potentials, the more electrons will flow; the greater the current will be.

Electricity is the same. When we attach a battery to a copper wire, the battery’s internal chemical reaction has created an electrical difference in potential. The negative terminal of a AA battery, has a higher potential than the positive terminal, so electrons will flow through the wire from the negative terminal to the positive. In this case, each coulomb of electrons will have the potential to do 1.5 joules of work as it passes through the wire.


Does Voltage Push or Pull Electrons?
The negative terminal of a AA battery repels electrons. This pushing force is what moves the electrons. However, we also know that electrons are attracted to a positive charge. So, are the electron being "pulled" by the positively charged battery terminal while being simultaneously pushed away by the negative terminal... or... does the negative terminal push the electrons away to a certain point, when the positive terminal begins to pull on them?

With water, the only force is gravity, which is a pulling force. But with flowing electrons, it seems like the water analogy would require a pump there is only a pull, and no push. I guess... if you use a water pipe instead of a lake, and you use a water pump as an analogy for the battery, the end where the water is pushed out of the pump would be the negative terminal, and on the other end, water is being sucked into the pump, so that would be the positive terminal. But could you say that the sucking action of the pump is pulling the water towards that end, or the pushing action of the negative end is pushing the water towards the positive end? or Both? If so to what degree, and when? Meaning... as a water molecule is pushed out of the pump, is the sucking end already acting on and affecting the molecule, or does the sucking action only exert force on the water molecule at a certain point?

It's all a real brain bender to me. Does anyone else know of a rock solid voltage analogy, or how I can improve this one?