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August 1960 Popular Electronics[Table of Contents] People old and young enjoy waxing nostalgic about and learning some of the history of early electronics. Popular Electronics was published from October 1954 through April 1985. All copyrights are hereby acknowledged. See all articles from Popular Electronics.
This electronics analogy quiz is a little easier than a few of the others published in Popular Electronics because all of the electrical and mechanical objects depicted here are very familiar. The concepts might seem trivial to those of us who have been immersed in the science for decades, but I for one can remember when first hearing these analogies how helpful they were. Not only that, but I also recall during physics and mechanics courses in college being amazed at the similarity of equations shared by electrical and mechanical processes.
By Robert P. Balin
Analogies - or comparisons - between electrical and mechanical phenomena are widely used to explain many electronic principles. See if you can match the lettered objects to the numbered symbols in the boxes below. The correct match in each case, and a complete explanation of the principles involved, will be found at the bottom of the page.
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Electronic Quizoo, October 1962
Analogy Quiz Answers
I. G. Because of its magnetic field, an inductor has the ability to resist any change in the amount or direction of the current flowing through it - we call this property "electrical inertia." A heavy grinding wheel, because of its mass, has mechanical inertia and tends to resist any change in its speed or direction of rotation.
2. D. A rectifier in an electrical circuit permits electron flow in only one direction. A ratchet wheel and check pawl likewise permit rotation in only one direction.
3. C. A capacitor stores electrical energy in its dielectric when it is charged, and the energy is recovered when you provide a discharge path for it. The coil spring in a jack-in-the-box stores mechanical energy in its stressed turns when the spring is compressed; this energy is recovered when you open the box.
4. H. A fuse element can carry little more than the normal current for its circuit; when an overload occurs, it is the first thing to burn in two and thereby open the circuit. The fuse may be compared, then, to the weakest link in a chain.
5. B. A resonant circuit will oscillate at a frequency determined by the inductance and capacitance present. A tuning fork oscillates as well, but at a frequency determined by its mechanical construction.
6. A. A transformer takes electrical energy supplied to its primary winding as a large current at low voltage and provides us with virtually the same amount of energy delivered as a small current at high voltage from its secondary winding. A gear train receives mechanical energy at high speed and low torque and converts it for use by a device requiring the same amount of power supplied at low speed and high torque.
7. E. An open switch stops electron flow in the same manner as a closed faucet stops the flow of water.
8. F. A resistor limits the current in a circuit, but converts some of the electrical energy into heat while doing so. The brake shoe on the wagon wheel limits the speed of its rotation, and changes some of the mechanical energy into heat.
Posted November 18, 2013