5C20.60 - Displacement Current

Code Number:
5C20.60
Demo Title:
Displacement Current
Condition:
Excellent
Principle:
Displacement Current
Area of Study:
Electricity & Magnetism

Disclaimer

Equipment:
Parallel plate capacitor, wave generator, Digital Oscilloscope, Coil Sensor (made from a spare Rowland Ring).
Procedure:

Set the wave generator at 1 MHz and connect it to the parallel plate capacitor and also to channel one of the oscilloscope so that you can monitor the input signal.  Connect the sensing coil to channel 2 of the oscilloscope.  When sensing inside the parallel plate capacitor you will get a signal that looks much like the input signal but will be slightly smaller and rougher looking.  Move the sensing coil to the outside of the positive plate and notice the signal is still there but a much smaller amplitude.  Moving the sensing coil to the negative plate will show no signal at all.  

 

 

References:
  • Carl, E. Mungan, "Surface Currents on the Plates of a Charging Capacitor", TPT, Vol. 59, #2, Feb. 2021, p. 86.
  • Joaquim Anacleto, J.M. Ferreira, "Comment on 'Magnetic Field Due to a Finite Length Current-Carrying Wire Using the Concept of Displacement Current'", TPT, Vol. 53, # 2, Feb. 2015, p. 68.
  • Robert Buschauer, "Magnetic Field Due to a Finite Length Current-Carrying Wire Using the Concepts of Displacement Current",  TPT, Vol. 52, # 7, Oct. 2014, p. 413.
  • Robert Buschauer, "Derivation of the  Biot-Savart Law from Ampere's Law Using the Displacement Current", TPT, Vol. 51, # 9, Dec. 2013, p. 542.
  • Gary Reich, "An Alternative Introduction to Maxwell's Displacement Current", TPT, Vol. 51, # 8, Nov. 2013, p. 485. 
  • Robert J. Sciamanda, "On Maxwell's Displacement Current - I", TPT, Vol. 38, # 6, Sept. 2000, p. 329.
  • Mark A. Heald, "On Maxwell's Displacement Current - II", TPT, Vol. 38, # 6, Sept. 2000, p. 329.
  • M. Alonso, E. J. Finn, "On Maxwell's Displacement Current - III", TPT, Vol. 38, # 6, Sept. 2000, p. 329.
  • A. P. French, "Is Maxwells's Displacement Current a Current?", TPT, Vol. 38, # 5, May 2000, p. 274.
  • Marcos G. Rizzotto, "Visualizing Displacement Current - A Classroom Experiment", TPT, Vol. 37, # 7, Oct. 1999, p. 398. 
  • R. W. Pohl, "The Displacement Current of the Dipole.  The Radiation of Free Electric Waves", Physical Principles of Electricity and Magnetism, p 323.
  • R. W. Pohl, "Electric Fields and Magnetic Fields", Physical Principles of Electricity and Magnetism, p 118.
  • Jose A. Heras, "A Formal Interpretation of the Displacement Current and the Instantaneous Formulation of Maxwell's Equations", AJP, Vol. 79, # 4, April 2011, p. 409.
  • N. Gauthier, "A Direct Derivation of the Displacement Current", AJP, Vol. 56, # 10, Oct. 1988, p. 871.
  • Harold S. Zapotsky, "Does Charge Conservation Imply the Displacement Current", AJP, Vol. 55, # 12, Dec. 1987, p. 1140.
  • A. J. Dahm, "Calculation of the Displacement Current Using the Integral form of Ampere's Law", AJP, Vol. 46, # 12, Dec. 1978, p. 1227.
  • W. G. V. Rosser, "Displacement Current in Maxell's Equations", AJP, Vol. 43, # 6, June 1975, p. 502.
  • Thomas R. Carver, Jan Rajhel, "Direct 'Literal' Demonstration of the Effect of a Displacement Current", AJP, Vol. 42, # 3, March 1974, p. 246.
  • H. L. Armstrong, "Comment of an Experiment Supposed to Show Displacement Current", AJP, Vol. 33, # 6, June 1965, p. 512.
  • Hans Meissner, "The Meaning of Experiments Designed to Demonstrate Displacement Current", AJP, Vol. 33, # 6, June 1965, p. 512.
  • Robert M. Whitmer, "Calculation of Magnetic and Electric Fields from Displacement Currents", AJP, Vol. 33, # 6, June 1965, p. 481.
  • Hans Meissner, "Demonstration of Displacement Current", AJP, Vol. 32, #12, Dec. 1964, p. 916.

Disclaimer: These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist.  The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose.  The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources.  Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks.  These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage.  Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.