6J11.10 - Retinal Fatigue - Bidwell's Disc

Code Number:
Demo Title:
Retinal Fatigue - Bidwell's Disc
Fatigue and After Images
Area of Study:
Optics, Human Biology
Variable Speed DC Motor, Compact Fluorescent Bulb with Red Jell, Half White Half Black Disc with a Section Cut Out, and 100 Watt Light Bulb in Desk Lamp.

Put the red bulb behind the cutout.  If the disc is spun so that you see the red bulb and then the white section of the disc the bulb will appear green.  If it is spun so that you see the red bulb and the black section of the disc the bulb remains red.

  • G. D. Freier and F. J. Anderson, "Oi-12", A Demonstration Handbook for Physics.
  • Richard Manliffe Sutton, "L-94. Complementary Colors Produced Subjectively", Demonstration Experiments in Physics.
  • Raymond Bruman, "Color Reversal", Exploratorium Cookbook I, p. 29.1 - 29.2.
  • Shoma Kutasov, "Bragg's Experiment", Physics Demonstrations, p. 273.
  • R.D. Edge, "13.01", String & Sticky Tape Experiments, p. 2.
  • Brian Jones and Matt Fackelman, "Red to Green", Don't Forget the Duct Tape, p. 117 - 120.
  • Robert J. Brown, "A Mystery Color Wheel", 200 Illustrated Science Experiments for Children, p. 81.

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