Hydraulic analogy

The electronic–hydraulic analogy (derisively referred to as the drain-pipe theory by Oliver Lodge) is the most widely used analogy for 'electron fluid' in a metal conductor. Since electric current is invisible and the processes at play in electronics are often difficult to demonstrate, the various electronic components are represented by hydraulic equivalents. Electricity (as well as heat) was originally understood to be a kind of fluid, and the names of certain electric quantities (such as current) are derived from hydraulic equivalents. As with all analogies, it demands an intuitive and competent understanding of the baseline paradigms (electronics and hydraulics).Conducting wire:  a simple pipe.Resistor: a constricted pipe.Node in Kirchhoff's junction rule: A pipe tee filled with flowing water.Capacitor:  a flexible diaphragm sealed inside a pipe.Inductor:  a heavy paddle wheel or turbine placed in the current.Voltage or current source:  A dynamic pump with feedback control.A simple one-way ball-type check valve, in its 'open' state acts as a diode in its conducting state.A pressure-actuated valve combined with a one-way check valve acts as a (field-effect) transistor.Like a one-way check valve, a diode blocks current that flows the wrong way. Current that flows the right way goes through almost unchanged.A simple A/C circuit consisting of an oscillating pump, a 'diode' valve, and a 'capacitor' tank. Any kind of motor could be used here to drive the pump, as long as it oscillates. The electronic–hydraulic analogy (derisively referred to as the drain-pipe theory by Oliver Lodge) is the most widely used analogy for 'electron fluid' in a metal conductor. Since electric current is invisible and the processes at play in electronics are often difficult to demonstrate, the various electronic components are represented by hydraulic equivalents. Electricity (as well as heat) was originally understood to be a kind of fluid, and the names of certain electric quantities (such as current) are derived from hydraulic equivalents. As with all analogies, it demands an intuitive and competent understanding of the baseline paradigms (electronics and hydraulics).