(8B10.50) Sunspots
$0.00
A light bulb on a variac is turned up to visible glow and placed on an overhead projector that is turned off. When the overhead is turned on, the filament appears as a dark spot.
$0.00
A light bulb on a variac is turned up to visible glow and placed on an overhead projector that is turned off. When the overhead is turned on, the filament appears as a dark spot.
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