Learning Difficulties and Teaching Strategies Related to Electric Circuits. David E. Meltzer Department of Physics and Astronomy Iowa State University Ames, Iowa. Research on Learning of Electric Circuit Concepts. Pre-college students Shipstone (1984) Early work with college students
David E. Meltzer
Department of Physics and Astronomy
Iowa State University
This exacerbates tendency toward confusion
Example: circuits? Exercise given in an elementary physics course:
(1) Draw a circuit diagram for the physical layout shown below (assume bulbs are identical)
(2) Draw a physical layout that corresponds to the circuit diagram shown below.
Results: Many students drew physical layout for #2
to be same as shown in first diagram!
It is EXTREMELY DIFFICULT to persuade students that these ideas are not correct!
[It is possible that some physicists may occasionally behave in a similar manner . . .]
Student: Same current goes through battery in each case; battery always has to produce the same amount of current.
Instructor: But since these bulbs are dimmer, doesn’t that mean that less current goes through these bulbs than through the bulb in the one-bulb circuit?
Student: Yes. The same current flows out of battery, but it is shared between the two bulbs, so each gets only half.
Result: 20% said readings would be different.
“Physics By Inquiry” and“Tutorials in Introductory Physics”: Extended hands-on investigations using batteries and bulbs.
1) Introduce concept of complete circuit: try to light bulb with wire and battery
2) Introduce concept of current: current not “used up”; current through a battery depends on circuit configuration.
3) Introduce concepts of resistance and equivalent resistance: “indicator” bulb with various configurations.
4) Introduce ammeters, voltmeters, and concept of potential difference.
5) Finally, introduce concepts of energy and power.
“Workbook for Introductory Physics”by Meltzer and Manivannan; for in-class use without relying on lab.