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L1-12. Inverse Square Law - Overhead Projector And Two-Meter Stick
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HomeL. Geometrical OpticsL1. Light Sources And Light RaysL1-12. Inverse Square Law - Overhead Projector And Two-Meter Stick
L1-12. Inverse Square Law - Overhead Projector And Two-Meter Stick
Purpose
To show that light obeys the inverse square law.
Equipment
Overhead Projector, two-meter stick.
Images
Description
With the lens one meter from the screen the area lit by the projector beam is measured. Moving the lens back to two meters from the screen, the width and height of the lit area both double, so the area is four times as great. The intensity is one-fourth for a distance of twice. This demonstrates that the inverse square law has as much to do with geometry as with wave propagation.
References
Simon George and Robert Doebler, Rainbow Glasses and the Inverse Square Law, TPT 32, 110-111 (1994).
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See pagesl1. light sources & light rays
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See pagesl2. plane mirrors
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See pagesl3. curved mirrors
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See pagesl4. refraction
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See pagesl5. total internal reflection
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See pagesl6. lenses
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See pagesl7. optical instruments
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See pagesl1. light sources & light rays
-
See pagesl2. plane mirrors
-
See pagesl3. curved mirrors
-
See pagesl4. refraction
-
See pagesl5. total internal reflection
-
See pagesl6. lenses
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See pagesl7. optical instruments
Physics Lab Demos