I saw a cute cartoon on facebook from yet another "suggested for you" that I immediately blocked. But it did describe current verses voltage verses resistance.
That's quite good John. I love simple analogies.
When I taught electrical to first and second year non-electrical engineers, I used a water system analogy. A wire is a pipe - some pipes are bigger (Internal Diameter = gauge) than others.
Voltage is like a water tower (battery) that produces water pressure. The higher the tank, the more pressure there is.
Amperage is the volume of water flowing in a pipe.
Resistance is like a restriction or orifice in the pipe or the length or diameter of the pipe.
You can have pressure without flow if everything is closed up. But you can't have flow without pressure.
Switches are like manual gate valves that are either open or closed.
Relays are like electrically controlled Switches.
Going beyond that to solid state stuff, diodes are like flap valves only allowing flow in one direction.
I always explained a FET before a transistor because...... Well because it is just easier to explain! LOL! FETs are like a valve that opens or closes based on the amount of pressure (voltage) applied through a diaphragm to a flow control valve. Just imagine a big diaphragm with lots of leverage to open or close even with small changes in pressure. I dunno about your cows on a Texas Gate! Whatever floats your boat! LOL!
Remembering that FETS are voltage controlled devices, now imagine a transistor as a similar valve that is controlled by current instead of voltage. The amount of water flowing through a control section opens or closes a variable valve to determine how much water flows through the big pipe. FETs are voltage (pressure) controlled, and transistors are amperage (current) controlled.
Capacitors are like little water tanks along the way that have a membrane inside at the midpoint so that whatever flows into them has to flow out the other side - either to ground or to the adjacent circuit - but they are only so big and therefore only hold so much. Once they are full, they are full. Sometimes you need bigger ones and sometimes they need to be little. It's easy to create delay circuits with a resistor and a capacitor.
Inductors are like long coils of low resistance pipe where the water has momentum - it takes a while to get it going and also takes a while to stop it. Think water hammer. I also compared it to a really long hose wrapped around a barrel. That made it easier to visualize a coil. Opening and closing the valve takes a while to affect what comes out the other end. The longer the hose, the longer the delay. Takes a little talking about starting and stopping a big ball rolling and perhaps a little faith to get past the hose expansion water storage issue but never found a better analogy.
DC is like a river flowing downhill. It only flows one way.
AC is like the bay of Fundy where the direction of flow changes depending on the tide constantly flowing in and out on a schedule determined by the moon and the sun which raise and lower the height of the ocean (voltage) outside the mouth (big resistor) of the Bay (big capacitor). In the Bay example, the frequency is just twice a day, but the household frequency is much faster at 60 times a second. Easy leap for most students to take.
Once a student can visualize and design a simple circuit, one can start to introduce the physics of how that happens with electrons in silicon. But it never ever made sense to me to start with the physics and then pray the students could understand the overall process. It's just easier to start with water towers, pipes, restrictions, valves, etc. Then make circuits everyone understands. Then transition the discussion to Volts Amps Resistance Capacitance Reluctance, Transistor Gain, etc etc. And then finally introduce circuit formulas and the physics. I firmly believe this produces students who understand and learn to enjoy electrical.
Digital logic systems are actually easier to explain. Just start with simple and/or/nand/nor decision circuits (gates) and then expand that to small integrated circuits which are just little rooms filled with tiny little people making decisions based on stupid rules made by all the dummies manning all the gates!
