The Effect of Temperature on the Braking Force Experienced by Magnet Falling Through a Copper Pipe

Authors

  • Miyu Bansal Glenunga International High School
  • John Duivestein

DOI:

https://doi.org/10.47611/jsrhs.v10i2.1503

Keywords:

Eddy Currents, Temperature, Dragging Constant, High School, Conducting Pipe, Magnet Fall, IB Extended Essay, Faraday's Law, Lenz' Law

Abstract

The braking experienced by a magnet falling through a conductive pipe is often shown in laboratories, as it is highly intriguing and captures the imagination of students. The Eddy current is the physical phenomenon behind Eddy current braking, which has a lot of utility as Eddy current brakes do not utilise friction and hence do not wear. Linear eddy current brakes, often used on rail vehicles, use the rail as a conductor. Consequently, it is important to address the impact of the rail's properties. Previous papers have explored the significance of thickness and material however temperature has yet to be considered.

Here, coils were wrung around a copper pipe and an oscilloscope was used to determine the position of a neodymium magnet falling through pipe at various temperatures in order to determine the magnet’s terminal velocity. This data was then used to determine the braking force exerted by the pipe on the magnet. The experimental findings were compared to a theoretical model for the braking force. Graphing the inverse of the dragging constant and temperature showed a positive linear relationship suggesting that increasing the temperature reduces the braking force experienced by the magnet, which is in line with pre-existing theory that increasing the temperature will reduce conductivity, in turn reducing the eddy currents that cause the braking force.

Finally, this study establishes that temperature, and hence the weather plays a significant role and needs to be considered when designing eddy current based machines, such as magnetic brakes in high-speed trains.

Downloads

Download data is not yet available.

References or Bibliography

The Editors of Encyclopædia Britannica, Eddy current, Encyclopædia Britannica inc. May 1, 2017. Accessed on: Nov. 27, 2019. [Online]. Available: https://www.britannica.com/science/eddy-current

Wikipedia contributors, Eddy current brake, Wikipedia, The Free Encyclopedia. Mar. 3, 2020. Accessed on: Nov. 2, 2019. [Online]. Available: https://en.wikipedia.org/wiki/Eddy_current_brake

The Editors of Encyclopædia Britannica, Faraday's law of induction, Encyclopædia Britannica inc. Sept. 6, 2013. Accessed on: Nov. 27, 2019. [Online]. Available: https://www.britannica.com/science/Faradays-law-of-induction

The Editors of Encyclopædia Britannica, Lenz’s law, Encyclopædia Britannica inc. Jan. 4, 2018. Accessed on: Nov. 27, 2019. [Online]. Available: https://www.britannica.com/science/Lenzs-law

D. Homer and M. Bowen-Jones, Physics Course Companion, 2014 ed. Oxford, England: Oxford University Press, 2014.

C. L. Ladera, G. Donoso, and P. Martín, “One or two magnets falling in a conductive pipe: On-axis and off-axis fall and the role of the pipe wall thickness,” Lat. Am. J. Phys. Educ, vol. 6, suppl. I, pp. 216-221, Aug. 2012. Accessed on: Dec. 1, 2019. [Online]. Available: http://www.lajpe.org/icpe2011/40_Celso_Ladera.pdf

B. Rizzato, F. L. da Silveira and Y. Levin, “Electromagnetic braking: A simple quantitative model,” Am. J. Phys. vol. 74, no. 9, pp. 815-817, Dec. 1, 2019. Accessed on: May 7, 2020. [Online]. Available: http://www.if.ufrgs.br/~levin/Pdfs.dir/AJP000815.pdf

C. L. Ladera, G. Donoso, and P. Martín, “Magnet fall inside a conductive pipe: motion and the role of the pipe wall thickness,” Eu. J. Phys. vol. 30, no. 4, pp. 855-869, May 2009. Accessed on: Dec. 1, 2019. [Online]. Available: https://pdfs.semanticscholar.org/0057/1f4604107499b4bb1713a2d4822b7a315631.pdf

F. G. Tomasel and M. C. Marconi, Rolling magnets down a conductive hill: Revisiting a classic demonstration of the effects of eddy currents, Am. J. Phys. vol. 80, no. 9, pp. 800-803, Sept. 2012. Accessed on: Aug. 7, 2019. [Online]. Available: http://www.msc.univ-paris-diderot.fr/~phyexp/uploads/LaimantParesseux/aimant2.pdf

K. Akhtar, The relationship between electrical conductivity and magnetically damped motion, Queensland Academy for Science, Mathematics and Technology. Accessed on: Aug. 7, 2019. [Online]. Available: https://digitalcommons.imsa.edu/cgi/viewcontent.cgi?article=1089&context=issf2018

Wikipedia contributors, Temperature coefficient, Wikipedia, The Free Encyclopedia. Mar. 1, 2020. Accessed on: Dec. 5, 2019. [Online]. Available: https://en.wikipedia.org/w/index.php?title=Temperature_coefficient&oldid=943452936

T. Forrister, How Eddy Current Braking Technology Is Freeing Us from Friction, COMSOL Blog, Mar. 2019. Accessed on: Nov. 2, 2019. [Online]. Available: https://www.comsol.com/blogs/how-eddy-current-braking-technology-is-freeing-us-from-friction/

L. Hanson, Northeastern IPL, Physics in Action: Magnet Falling Through a Conductive Pipe, May 16, 2017. [Video file]. Available: https://www.youtube.com/watch?v=2-iEVFICIqM

Wikipedia contributors, Thermal expansion, Wikipedia, The Free Encyclopedia. May 6, 2020. Accessed on: Dec. 5, 2019. [Online]. Available: https://en.wikipedia.org/w/index.php?title=Thermal_expansion&oldid=955208327

The Editors of Encyclopædia Britannica, Newton’s laws of motion, Encyclopædia Britannica inc. Feb. 3, 2020. Accessed on: Nov. 27, 2019. [Online]. Available: https://www.britannica.com/science/Newtons-laws-of-motion

“Rare Earth (Neodymium) Cylinder Magnets,” AMF Magnetics, 2020. Accessed on: Aug. 5, 2019. [Online]. Available: https://magnet.com.au/rare-earth-magnets-neodymium-cylinders.html

J. Tatum, The SI Definition of Magnetic Moment, Physics LibreTexts. Jun. 3, 2019. Accessed on: Nov. 27, 2019. [Online]. Available: https://phys.libretexts.org/Bookshelves/Electricity_and_Magnetism/Book%3A_Electricity_and_Magnetism_(Tatum)/17%3A_Magnetic_Dipole_Moment/17.02%3A_The_SI_Definition_of_Magnetic_Moment

A. Nájera, A. Beléndez, C. P. Suárez, E. Arribas and I. Escobar “Measurement of the magnetic field of small magnets with a smartphone: a very economical laboratory practice for introductory physics courses,” Eu. J. Phys. vol. 36, no. 6, pp. 1-12, Aug. 2015. Accessed on: Dec. 1, 2019. [Online]. Available: https://pdfs.semanticscholar.org/6fdd/153d69bcb9c00587e3926903cfed90c897c9.pdf

Wikipedia contributors, Electrical resistivity and conductivity, Wikipedia, The Free Encyclopedia. May 5, 2020. Accessed on: Nov. 23, 2019. [Online]. Available: https://en.wikipedia.org/w/index.php?title=Electrical_resistivity_and_conductivity&oldid=954934185

“Typical Magnetic Properties for Rare Earth Magnets,” AMF Magnetics, 2020. Accessed on: Feb. 5, 2020. [Online]. Available: https://magnet.com.au/typical-magnetic-properties-for-rare-earth-magnets.html

The Plumbers Handbook, 9th ed. International Copper Association Australia, Copper Alliance, Australia, Mar. 2016, p. 10. Accessed on: Dec. 5, 2019. [Online]. Available: https://www.kembla.com/assets/Uploads/general-PDFs/The-Plumbers-Handbook-9th-Edition.pdf

D. Chapman, High Conductivity Copper for Electrical Engineering, Copper Development Association, Copper Alliance, Dec. 5, 2019. Accessed on: May 7, 2020. [Online]. Available: http://copperalliance.org.uk/uploads/2018/02/pub-122-hicon-copper-for-electrical-engineering.pdf

Published

07-01-2021

How to Cite

Bansal, M., & Duivestein, J. (2021). The Effect of Temperature on the Braking Force Experienced by Magnet Falling Through a Copper Pipe. Journal of Student Research, 10(2). https://doi.org/10.47611/jsrhs.v10i2.1503

Issue

Section

IB Extended Essays