Water analogies [Re: one for the theorist]

[KA4HJH]

>>Anyway, the water example is nice. Now: what is the water equivalent of a
>>capacitor?
>>I guess a pressure container with some air in it?
>
>Gravity? Imagine an open topped cistern with pipes in and out. As the
>water level rises so does the pressure.

Gravity doesn't work well in this analogy. Here's the one I've always used:
imagine a cylindrical container with pipes attached at the ends. In the
middle there is a flexible membrane. If the pressure is greater on one
side, this will distend the membrane, displacing water from the other side.
Too much pressure and it will burst. :o

Polarized capacitors, anyone?

A rectifier is a check valve. The pressure required to open the valve
(typically held shut by a spring) is analagous to the drop across the PN
junction.

There's a type of crude water pump that's sort-of like a switching power
supply, if you go by these analogies (it does involve gravity).

Terry Bowman, KA4HJH
"The Mac Doctor"