20 minutes into my first electronics class, and everything was going smoothly. For a start, I no longer had to do woodwork — there were no hacksaws, no clamps, and no godforsaken dovetail joints. As someone whose hands might well be on backwards, this was great news. “Electronics is just maths,” I thought, “I’m good at maths. Hell, I’m one of the few who actually likes maths.”
At that point, my teacher uttered the oh-so-innocent-sounding words: “An electrical circuit is like a water tank …”
That’s when it all went wrong.
I’ve always associated my tech-imposter syndrome with my inability to understand electronics. These circuits lurk — with all their sparks and plugs — underneath the computer’s hood, waiting to go wrong. Generally, this isn’t a problem. As with the Earth’s surface, we happily stroll around, unconcerned about the magma beneath. But sometimes that magma rises out, causing untold damage. Okay, perhaps that’s a bad analogy.
Speaking of bad analogies, for those who don’t know the Electrical Circuit As A Water Tank comparison, I’ll do my best to explain. No promises though because, as you will see, I never did manage to get this right.
First thing’s first. There are three basic parts of an electrical circuit: current, voltage and resistance. Current is the flow of electrical charge. Voltage is the energy, which ‘pushes’ the charge around. Resistance opposes the flow.
Voltage is abbreviated to V. Resistance is shortened to R. Current, strangely, becomes I. (I don’t know why this is the case. I like to think it’s a piece of old-school-science poetry, short for something like Incandescence or Irascibility.)
Next up is Ohm’s law. This combines all three parts into one neat equation: Voltage = Current x Resistance. V = IR. Easy, right? Hmmm … I’ll come back to this.
Finally, we reach the WaterTank analogy. It’s a convenient but, to my simple mind, flawed comparison, which is taught the world over. Here, the water (electrical charge) is high up in — you guessed it — a tank. Gravity (voltage) causes that water to flow (current) downwards, out through a pipe. The width of the pipe represents resistance.
This model may well work for most people. For me, it is a source of great confusion.
On hearing the analogy, my first thought was: aren’t we meant to keep electricity away from water? I know, I know, that’s not how analogies work. Still, I couldn’t shake that nagging feeling, as if someone had said “A friendly handshake is like poking someone in the eye … “
My second thought was: I’ve never seen a water tank system. The closest I’d ever got was playing with a garden hose. If I put my finger over the end of the hose, the water sprays further. Does that actually work with this model?
My brain was firing in all directions, and finding nothing but more questions. That’s the danger of relying on similarities — some people’s minds will naturally linger on the differences.
Here is one such difference. An electric circuit is circular. The water tank system, as described, is linear — it has a definite beginning, middle, and end. This may seem trivial, but Ohm’s law defines a circular relationship. That’s something they — teachers, textbooks, dry informative TV — really wanted to hammer home.
This circular nature completely fries my neurons (man). My mind gets trapped in an infinite loop of V’s and I’s and R’s. There seems to be no foothold to push off from.
Whenever I tell people of my confusion, they stare at me with this blank look on their face, as if I’m being deliberately obtuse. This is kid’s stuff, they’re thinking. Probably. (There’s that damned Imposter Syndrome again.)
I can see why it should be obvious. For a start, there’s such a thing as batteries. These kick the whole system off, and are my elusive foothold. But batteries come in different voltages, which suggests some pre-existing knowledge about current and resistance. At which point I’m back in my infinite loop, not knowing what comes first, or how to use each piece of information.
Perhaps my real problem with the analogy is that it’s too focused on the tank, rather than its overall goal. Not in the sense of the tank’s life ambitions, and where it sees itself in 5 years. More like, what problem is being solved by the combination of each part. Why do we have thinner pipes in some places? Similarly, in an electrical circuit, why do we use different resistances?
It’s also likely that analogies aren’t for me, at least in this context. Since struggling with the water tank idea, I’ve looked for other models that do click. I’ve read about cars and jewels, buildings and ladders, rocks and hills. I’m still none the wiser.
So — with my ignorance laid out on the table — I’ll ask again: why would you put a electricity in a water tank?