Candela

something is. It is one of the basic units of science. A light bulb is bright, but the Sun is much brighter, so the Sun has more candelas than the light bulb. The frequency chosen for measuring candelas falls within the visible spectrum near the green colour, corresponding to the wavelength of about 555 nanometres (nm). The human eye is most sensitive to such frequency, when adapted for bright conditions.

A candela sometimes is called "candle".

Candela Media

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  1=radiating tube of thorium dioxide; 2=melting pot; 3=solidifying platinum