Question

light intensity used to be measured according to this................... but it has to start with RA

Answer 1

Answer:

See below

Explanation:

The lux (symbol: lx) is the SI unit of illuminance and luminous emittance, measuring luminous flux per unit area. It is equal to one lumen per square metre. In photometry, this is used as a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface.

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