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Al Tobias (wat4y) - Office: Gibson S123 & Physics 218, (434) 924-0538

Physics Demo Manual

Demonstrations are cataloged according to PIRA Bibliography


Due to Physics Building renovations, the lead time to set up demo requests has increased due to the need to transport equipment across campus. Please be kind and let me know well ahead of time what you need.

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 Geometrical Optics
 The Eye
 The Eye Model I
 The Eye Model II
 Image Retention

The Eye Model II


Demonstrate the optics based principles of the human eye.


Use the PASCO "whiteboard" laser ray set up with the human eye template (template A). Using the lenses with different focal lengths (curvature) demonstrate that the focal point of different lenses isn't always on the eye retina. Show that short-sightedness (Myopia) and far-sightedness (Hyperopia) can be corrected for using lenses (glasses).

In the kit, lens #1 shows a healthy cornea that requires no correction (focus is on the retina). Lens #5 shows a (near) short-sighted cornea since the focus occurs before the retina. Using a diverging "glasses" lens #2 corrects the focus onto the retina. Lens #4 shows a (far) long-sighted cornea since the focus occurs beyond the retina. Using a converging "glasses" lens #3 corrects the focus onto the retina.


Try to convince the students they understand why it is called "near" and "far" sightedness.