PURPOSE: To demonstrate that a lens focuses light.
DESCRIPTION: The black housing at the left in the picture contains a clear bulb with a W-shaped filament, which can be focused on a distant screen at the right. With the lens rotated out of the light from the source, several pinholes are poked into a sheet of tin foil covering one end of the aluminum tube in the center of the photograph, producing several pinhole "images" on the screen. When the lens is rotated back into the light, all of the images from the pinholes are combined into a single true image.
REFERENCES: (PIRA 6A60.50)
EQUIPMENT: Object lamp, mounted tube with pinhole foil, lens on rotating mount, on optical rail cart.
SETUP TIME: 5 min.
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