Overhead Projector, Block, Rulers
Block and Rulers
Block and Rulers

 

Code Number: 6A40.10

Demo Title: Apparent Depth - TV & Overhead Projector

Condition: Excellent

Principle: Geometrical Optics

Area of Study: Index of Refraction

Equipment:

Plastic Block, Transparent Ruler.

Procedure:

Place the block from the blackboard optics set on the overhead projector with a transparent ruler underneath it.  Turn on the overhead projector and then take another transparent ruler, raise it until both rulers appear the same size.  Measure how high you have raised the ruler and you should be able to calculate the index of refraction of the block.  

You can do the same thing by using a video camera instead of the overhead projector.

References:

  • Jun Wang, Yewen Zhu, Wenqing Sun, "An Unexpected Observation in an Underwater Optical Experiment", TPT, Vol. 62, #6, Sept. 2024, p. 515.
  • Arne Bewersdorff, David Weiler, "Measuring the Speed of Light in Liquids with a Smartphone", TPT, Vol. 60, #6, Sept. 2022, p. 516.
  • George D. Freier, "Geometrical Optics", TPT, Vol. 33, #6, Sept. 1995, p. 32
  • George Schuttinger, "Cornea vs Lens", TPT, Vol. 33, #5, May. 1995, p. 263.
  • Gordon O. Johnson, Albert A. Bartlett, and Eugene Mosca, "Further Illuminating Comments on Rays and Images", TPT, Vol. 33, #4, Apr. 1995, p. 198.
  • Antonio B. Nassar, "Apparent Depth", TPT, Vol. 32, #9, Dec. 1994, p. 526.
  • G. Sauer, "Measuring the Refractive Index with the Overhead Projector", TPT, Vol. 19, #6, Sept. 1981, p. 426
  • Albert A. Bartlett, Rodger Lucero, and Gordon O. Johnson, "Note on a Common Virtual Image", AJP, Vol. 52, #7, July 1984, p. 640.
  • Seiji Ono, "Lecture Hall Determination of the Position of a Virtual Image", AJP, Vol. 48, #4, April 1980, p. 322.
  • G. D. Freier and F. J. Anderson, "Od-6", A Demonstration Handbook for Physics.
  • "O-220. Ruler Under Beaker or Block", DICK and RAE Physics Demo Notebook.
  • Robert Ehrlich, "P.8. Apparent Depth of a Submerged Object", Turning the World Inside Out and 174 Other Simple Physics Demonstrations, p. 182 - 183.