The solenoid : what's there to learn further about a passive component that is nearly 200 years old, dating back to the 1820s? After all, it's a simple passive component, isn’t it? And there is not that much to understand, right?
Well, yes and no. This article examines the common claim that the strength of a solenoid can be increased by removing some turns from the coil. In the process we look at formulations for inductance, power, energy, and force. The end result clarifies the roles of several solenoid parameters, and the effect of the number of turns may be surprising to many readers. Those who would prefer to skip the mathematical details can find a qualitative explanation in the conclusion.
We are presenting this article—which includes equations, models, and analysis—in three parts, as pdf files:
Part 1 : Introduction; Equivalent Circuit; to read it, click here .
Part 2 : From Energy to Force; Additional Discussion; to read it, click here.
[Editor's note: some readers have reported that Part 2 equations are not rendering properly in the pdf. If that's the case for you, please try this alternate version here, where Part 2 starts at the bottom of the first pdf page “From Energy to Force”, and ends with the beginning of Part 3 (Conclusion).]
Part 3 : Conclusion; References; and Appendix; to read it, click here .
About the author
Paul H. Schimpf holds the B.S., M.S., and Ph.D. degrees in Electrical Engineering from the University of Washington, with respective degree specialties in digital electronics, embedded signal processing, and modeling electromagnetic fields in complex domains such as the human body.