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What is the unit of luminous intensity used prior to 1948, equal to the luminous intensity of a wax candle of standard specifications?

• Foot-candle

• Lumen

• Lux

• Candela

What is the law that the illumination produced on a surface by a point source is proportional to the cosine of the angle of incidence?

• Inverse square law

• Cosine law

• Ohm's law

• Lambert's law

What is the SI unit of illumination, equal to one lumen per square meter?

• Lux

• Candela

• Lambert

• Foot-candle

What is a unit of length equal to one ten-billionth of a meter, used especially to express the wavelengths of radiation?

• Angstrom

• Micrometer

• Millimeter

• Nanometer

What is the sensation by which an observer is able to distinguish between differences in luminance?

• Radiance

• Brightness

• Luminance

• Illumination