5M10.61 - P-N Junctions - Gravitational Model

Code Number:
Demo Title:
P-N Junctions - Gravitational Model
Forward Bias
Area of Study:
Electricity and Magnetism
P-N Junction Gravitational Model, 1 Inch Ball Bearings, and 3 Blocks (Optional).

Place the model so that it is level on a table.  Without any blocks, place the ball bearings on the lower hinged rail.  Lift that rail and when you reach the correct amount of "forward bias" the balls will role down the rail and into the box with the holes.  An option is to use the blocks to put under the rail until the ball roll into the box with the holes.  The top of the box is held in place magnetically for ease of bearing retrieval.

  • Victor E. Henrich, "Gravitational Model of a p-n Junction", TPT, Vol. 56, #8, Nov. 2018, p. 538.
  • Victor E. Henrich, "Motivating Non-Science Majors: The Technology of Electromagnetic Waves", TPT, Vol. 56, #1, Jan. 2018, p. 29.
  • Tim Gfroerer, Ken Rathbun, "Squiggle Ball Capture: A Simple, Visual Kinetic Theory Experiment", TPT, Vol. 45, # 6, Sept. 2007, p. 344.
  • A. Sconza, G. Torzo, G. Viola, "Experiment on the Physics of the PN Junction", AJP, 62, # 1, Jan. 1994, p. 66.
  • Peter J. Collings, "Simple Measurement of the Band Gap in Silicon and Germanium", AJP, Vol. 48, #3, March 1980, p. 197.
  • Qing Cao, Jerry Tersoff, Damon B. Farmer, Yu Zhu, Shu-Jen Han, "Carbon Nanotube Transistors Scaled to a 40-nonometer Footprint", Science, Vol. 356, # 6345, June 30, 2017, p. 1369.

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