5C20.22 - Forces on a Dielectric

Pour Silicon Oil into the Petri dish to a depth of 1/4 inch. Place the electrodes into the dish and space them about 1/8 in apart. The higher you turn up the voltage on the power supply, the higher the oil will climb in the gap between the electrodes. The oil should rise at least 1 to 1.5 cm up into the gap.
Caution: If you turn the voltage up too fast you will get arcing of the electrodes. Turn the voltage down and then up slowly. As the oil rises into the gap you will be able to apply more voltage. If the electrodes are too close together, you will also get continuous arcing between them and the demo will fail.
Mineral oil may be substituted for the Silicon oil but it will not rise up into the gap as far.
Code Number:
5C20.22
Demo Title:
Forces on a Dielectric
Condition:
Excellent
Principle:
Forces on Dielectrics
Area of Study:
Electricity & Magnetism

Disclaimer

Equipment:
High Voltage Power Supply, Aluminum cylinder electrodes, Silicon Oil, Mineral Oil, 6 inch Petri Dish.
Procedure:

Pour Silicon Oil into the Petri dish to a depth of 1/4 inch.  Place the electrodes into the dish and space them about 1/8 in apart.  The higher you turn up the voltage on the power supply, the higher the oil will climb in the gap between the electrodes.  The oil should rise at least 1 to 1.5 cm up into the gap.  

Caution:  If you turn the voltage up too fast you will get arcing of the electrodes.  Turn the voltage down and then up slowly.  As the oil rises into the gap you will be able to apply more voltage. If the electrodes are too close together, you will also get continuous arcing between them and the demo will fail.

Mineral oil may be substituted for the Silicon oil but it will not rise up into the gap as far.

References:
  • Chen Xuan, "Enlightening Visualizations of Partially Filled Dielectric Capacitors", TPT, Vol. 61, #6, Sept. 2023, p. 503.
  • Eric R. Dietz, "Force on a Dielectric Slab: Fringing Field Approach", AJP, Vol. 72, # 12, Dec. 2004, p. 1499.
  • F. N. Yan and H. K. Wong, "Force Between the Plates of a Parallel-Plate Capacitor", AJP, Vol. 61, #12, Dec. 1993, p. 1153.
  • S. Margulies, "Force on a Dielectric Slab Inserted into a Parallel-Plate Capacitor", AJP, Vol. 52, #6, June 1984, p. 515.
  • F. X. Hart and J. S. Massey, "Two Electrohydrodynamic Demonstrations", AJP, Vol. 49, #7, July 1981, p. 695.
  • Robert A. Morse, " # 4, The Flexible Capacitor: Connecting Electrostatics and Batteries", Teaching about Electrostatics, p. 4 - 5.
  • Robert A. Morse, "The Flexible Capacitor: An Electrostatic Demonstration Using Batteries", TPT, Vol. 30, #1, Jan. 1992, p. 22.
J4-24: Force on Dielectric in Electric Field
EM-c2c: Force on a Dielectric

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