June 23, 2013
June 23, 2013
June 26, 2013
Technological and Engineering Literacy/Philosophy of Engineering
23.371.1 - 23.371.9
Demonstration of Electrical Principles in the Classroom by Hydraulic AnaloguesHydraulic analogies for the basic three circuit elements have been known for many years, andsome practical and inexpensive physical examples have recently been built and used in basiccircuit laboratories. Since non-engineering majors, as well as non-electrical engineering majors,are typically mystified by electricity, these basic three hydraulic models are effective in breakingdown the “mystification factor” concerning basic electricity.Electricity cannot be seen (except as lightning, or other high-voltage or high-currentphenomena). Many students decide to study engineering because they have had mechanicalexperiences, such as fixing cars or tractors at home. The “feel” for mechanical things is alreadythere; you push it, and it moves. Not so with electrical things.In order to present electrical concepts to students unfamiliar with electricity, analogies arehelpful. Some thought experiments and analogies are presented to help communicate electricalconcepts to lay people, and have recently been used to successfully explain basic electricalconcepts to children 10 to 14 years of age. Actual laboratory experiments, using water resistors,water capacitors, water ammeters, water voltmeters, and balloons, have been used in laboratoryexperiments in our curriculum for several years now, and these experiments have becomeeagerly anticipated in the basic engineering circuits class at ------------ university.Students learn new concepts by comparing them to things with which they are already familiar.One of our problems with the present generation is that students tend not to be as physicallyactive as they were in previous generations. We have fewer “farm boys” and “shade treemechanics” coming in as freshmen. They may never have siphoned water, played with “frictionmotor” cars, or gyroscopes. They may have no idea that flowing water has inertia, that waterpressure in your house is due to the water tower in your town, and that water pressure can beused to cut metal. A hydraulic circuits lab can help them understand both hydraulic and circuitsconcepts. A hydraulic resistor loses energy by forcing water through a constriction in a pipe. A hydrauliccapacitor, made by separating two chambers by a rubber membrane, stores energy. This is apotential energy source. Inductance is related to kinetic energy. A moving stream of water hasinertia by virtue of its mass, but the addition of a flywheel and paddles increases that inertia.Thus, kinetic energy is stored in a hydraulic inductor.If the hydraulic inductor is connected to the hydraulic capacitor, in a closed hydraulic circuit, thesystem can be made to oscillate. The oscillation can also be compared to the action of apendulum.Interaction at a recent workshop on the assessment of “Technological Literacy” and “HowThings Work” courses, funded by the National Science Foundation, indicated that the hydraulicanalogy to circuit theory would be helpful in educating non-STEM students. The use ofhydraulic models for many electrical concepts, and details on construction of the components areincluded.
Graff, R. W., & Leiffer, P. R. (2013, June), Demonstration of Electrical Principles in the Classroom by Hydraulic Analogues Paper presented at 2013 ASEE Annual Conference & Exposition, Atlanta, Georgia. https://peer.asee.org/19385
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