  Reasoning by analogy is powerful in physics for students and researchers
alike, a case in point being electronics and hydraulics as analogous studies of
electric currents and fluid flows. Around 100 years ago, Nikola Tesla proposed
a flow control device intended to operate similarly to an electronic diode,
allowing fluid to pass easily in one direction but providing high resistance in
reverse. Here we use experimental tests of Tesla's diode to illustrate
principles of the electronic-hydraulic analogy. We design and construct a
differential pressure chamber (akin to a battery) that is used to measure flow
rate (current) and thus resistance of a given pipe or channel (circuit
element). Our results prove the validity of Tesla's device, whose anisotropic
resistance derives from its asymmetric internal geometry interacting with
high-inertia flows, as quantified by the Reynolds number (here, Re ~ 1e3).
Through the design and testing of new fluidic diodes, we explore the
limitations of the analogy and the challenges of shape optimization in fluid
mechanics. We also provide materials that may be incorporated into lesson plans
for fluid dynamics courses, laboratory modules and further research projects.
