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A lamp is a replaceable component such as an incandescent light bulb, which is designed to produce light from electricity. These components usually have a base of ceramic, metal, glass or plastic, which makes an electrical connection in the socket of a light fixture. This connection may be made with a screw-thread base, two metal pins, 2 metal caps or a bayonet cap.

Light Fixture

A lamp is a replaceable component such as an incandescent light bulb, which is designed to produce light…

"Another illustration of how luminous density varies inversely as the square of the distance." —Croft 1917

Light Intensity Versus Distance

"Another illustration of how luminous density varies inversely as the square of the distance." —Croft…

"Let us suppose that a, is a luminous point, from which a pencil of diverging rays falls upon a convex mirror. These rays, as already demonstrated, will be reflected more divergent, and consequently will meet the eye at e, in a wider state of dispersion that they fell upon the mirror at o." -Comstock 1850

Convex Mirror

"Let us suppose that a, is a luminous point, from which a pencil of diverging rays falls upon a convex…