6A42.40 - Refraction - Penny & Cup

See paragraph one in the procedure section
Code Number:
Demo Title:
Refraction - Penny & Cup
Refraction of Light Waves
Area of Study:
Styrofoam cup, penny, water.

 Place the cup on the bench with the penny inside and towards one side of the cup.  Look into the cup and slowly back away until the penny is no longer visible.  Without moving your eyes from their position, pour water into the cup and notice that the penny reappears when the cup is full of water.

  • Od-4:  Freier and Anderson,  A Demonstration Handbook for Physics.
  • Charles Vivian, "Penny in a Bowl", Science Experiments & Amusements For Children, p. 74.
  • Martin Gardner, "57, The Vanishing Coin", Smart Science Tricks, p. 88.
  • Martin Gardner, "Vanishing Postage Stamp", Entertaining Science Experiments with Everyday Objects, p. 75.
  • Vicki Cobb and Kathy Darling, "Odds That Are Out of Sight", Bet You Can't!, p. 95.
  • "The Coin-in-the-Cup Experiment", The Boy Scientist, p. 181.
  • Janice VanCleave, "35, Where's the Penny?", Teaching the Fun of Physics, p. 57.
  • Tik Liem,  "The Reappearing Coin", Investigation to Science Inquiry, p. 277.
  • Tik Liem, "11.13, Why Do We See Two Coins?", Investigation to Science Inquiry, p. 283.

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