A Shockingly Good Analogy

 Have you ever been at a dinner party and someone said “I wish I knew a good analogy describing how electricity flows through wires?” Yeah, me either. But if you ever find yourself in this pesky situation, here’s an article from Ask Dr. Ben. 


Electrical flow is almost completely analogous to water flowing in a pipe. Pressure is Voltage, current is flow (volume of water, or charge, per second) and resistance is effectively the size of the pipe.


A high voltage (pressure) in a big pipe (low resistance) yields a whole lot of flow. Conversely, low voltage in a clogged pipe gets you a trickle.  To address wattage (Power = Current x Voltage, after all), just imagine asking how quickly you could pick up a car with a hydraulic piston. More voltage (pressure) and current means you’ll flood the hydraulic chamber and lift the piston faster.

This of course assumes DC (“direct current”, or constant voltage), but alternating current (AC) doesn't strain the analogy either. Just imagine a piston/plunger going back and forth in a closed volume. It sucks and blows back and forth but there is definite flow. And flow can do work, even if it needs a check valve or two to push in one direction. Either way, a high resistance restricts how much water you can move.

Basic circuit elements are easily modeled too. A capacitor is little more than a tank. A resistor is just a small diameter pipe stuck in line with a larger set of plumbing. A transistor is a pressure switch. An inductor coil is like a little turbine inside the pipe (resists when “spinning up”, but then tries to maintain current flow when being turned off). And yes, a diode is a “check valve”, both are just one-way gates to flow.

There’s actually a branch of engineering called Fluidics which leverages this similarity: https://en.wikipedia.org/wiki/Fluidics