A Fan-tastic Alternative to Bulbs: Learning Circuits with Fans

Abstract

The incandescent bulb has been a useful tool for teaching basic electrical circuits, as brightness is related to the current or power flowing through a bulb. This has led to the development of qualitative pedagogical treatments for examining resistive combinations in simple circuits using bulbs and batteries, which were first introduced by James Evans and thoroughly expanded upon by McDermott and others. This paper argues that replacing bulbs with small computer fans leads to similar, if not greater, insight of experimental results that can be qualitatively observed using a variety of senses. The magnitude of current through a fan is related to the frequency of the rotating fan blades, which can be seen, heard, and felt by the students. Experiments using incandescent bulbs only utilize vision, which is not ideal as the human eyes’ perception of brightness is skewed because the response to light intensity is logarithmic rather than linear.

A Fan-tastic Quantitative Exploration of Ohm’s Law

“…These results agree with the qualitative observations that were previously reported for the same combination circuits in Ref. 10. For example, with a combination circuit where two fans are in parallel with one in series, you would expect the speed of the fans in parallel to be the same and significantly slower than the fan in series, which was observed.…”

“…Overall, when within operational range, the experimental values are in good agreement with those calculated using Ohm's law, which also validate the qualitative observations previously reported. 10 Fan circuits with different effective resistances A different fan model (Multicorp -MC36256) was also identified to be capable of demonstrating simple circuit behaviors. 10 This fan model has a higher threshold voltage (~3 V) than the ADDA fans; however, once the supply voltage sufficiently exceeded this value, an ohmic behavior was observed.…”

“…10 Fan circuits with different effective resistances A different fan model (Multicorp -MC36256) was also identified to be capable of demonstrating simple circuit behaviors. 10 This fan model has a higher threshold voltage (~3 V) than the ADDA fans; however, once the supply voltage sufficiently exceeded this value, an ohmic behavior was observed. After plotting the VI curve and taking the slope, the Multicorp fans yielded a consistent effective resistance of 27.1 Ω ± 5%.…”

“…Recently, small computer fans were proposed as a suitable replacement of bulbs for qualitative analysis of simple circuits where the current is related to the rotational speed of the fans. 10 In this contribution, we demonstrate that fans can also be used for quantitative measurements and provide suggestions for successful classroom implementation.…”

Gender Effects in a General Physics Laboratory Assessment

“…The fans allow students who are visually impaired to use a tactile response to sense how much current is flowing through a fan motor. 7 The College of Engineering & Science at the University of Detroit offers two physics sequences, one algebra-based and one calculus-based. The calculus-based general physics sequence is a requirement for all engineers and for chemistry majors.…”