Beginner overview of electricity, using the water analogy… What do you think?-

Electricity seems very difficult for most people to understand. You can’t properly see it, you can’t properly feel it and you can’t taste it or smell it so what is it? It travels quite well through metals and generally poorly through non-metals. It doesn’t behave quite like anything else.

But this is not quite true: fluid flowing through a system of pipes can behave in many respects like electricity flowing in a circuit. The ‘obvious’ exception to this is that if you pierce a pipe full of water, the water comes out.

Try piercing the insulation and touching the conductor: you will soon find the electricity coming out! The main difference is that water will fill any space whereas electricity will ‘fill’ only a conductor. Yes – the analogy is not perfect, but it is helpful and understanding will come not only from the similarities but also from the differences.

4QD-TEC: Understanding Electricity – Link.

## 16 thoughts on “Understanding electricity (water analogy)”

1. an EE says:

That’s terrible.

2. Tommy says:

I used water as a sorta-analogy in college electronics classes. Certainly helped me get an A.

It’s not perfect at all, but it does help give a handle on some of the base concepts. Once you have those concepts down, you can drop the analogy.

3. GregS says:

Thinking of electricity as water does help visualize how it acts, as long as you don’t push the analogy too far. Electricity can be seen to be like water, conductors as being like pipes or channels, resistors as being like narrowing of a pipe to reduce flow, capacitors as being like tanks, diodes as being like one-way valves, voltage as being like water pressure, etc. But the analogy breaks down if you push it too far – there’s no positive and negative water, water is not attracted to anything, there’s really no equivalence to magnetism with water or to electrical phenomena related to magnetism, like inductance or electromagnetism. So I think it can be a useful way to introduce people to the behavior of electricity, but you have to leave the analogy behind pretty quickly.

4. Matt says:

I’m all systems and no electrical. He lost me completely with capacitance. Capacitance is like square footage, and coulomb is volume. I get volume, but I don’t see the area-relationship with electricity. Anyone care to re-explain?

5. An EE says:

Except for the fact that electricity/electrons move at the speed of light, and the speed is not affected by the voltage, the water pressure analogy’s not bad. (it’s the average directionality, and the average number of moving electrons that the voltage affects). Things move when you push them. (And I’ve used the garden hose sprayer as an analogy for a transistor)

A lot of times, I use a ping-pong balls in a tube analogy – you pop a ping pong ball into one end, another one pops out the other end. The discrete ping-pong ball elements seems to help people illutrate the quantum nature of electrons better than water. A bigger pipe, and more ping pong balls can pass through at once. LIke water, Narrow the pipe, and fewer balls get through the narrow pipe. But once again, the speed/pressure analogy breaks down.

6. Jack says:

The book “Practical Electronics for Inventors” (by Paul Scherz) pushes the water analogy pretty far, and quite successfully. I’d recommend this book to any electronics hobbyist (though I hope future editions go into even more depth on uC’s. It does have a number of great generic uC circuits, though)

7. Jack says:

The book “Practical Electronics for Inventors” (by Paul Scherz) pushes the water analogy pretty far, and quite successfully. I’d recommend this book to any electronics hobbyist (though I hope future editions go into even more depth on uC’s. It does have a number of great generic uC circuits, though)

8. NotAnEE says:

Hate to be all pedantic but electricity just doesn’t move at the speed of light in a conductor.

Its about 0.7c for the usual voltage / conductor characteristics.

9. A ME/EE says:

An EE,
Electrons do not move at the speed of light through a circuit- only the wave of voltage change propagates at that speed. The speed of individual electrons will definitely be dependent on current (directly) and voltage (indirectly).

The analogy in fluid systems would be the propagation of a wave of pressure change propagating at the speed of sound- independent of the pressure. The speed of individual fluid quanta (atoms or molecules) will be dependent on flow rate (directly) and pressure (indirectly).

As far as magnetic effects, there are ways to model analogous effects in pressure systems, but they are a bit contrived.

10. Dishwasher says:

That’s really interesting!

11. ramonacole says:

And did you know that water flow can be measured in many units but we are using feet? So let’s keep to cubic feet per second to measure flow rate. The electrical equivalent is Amperes (amps). Write my essay for me

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