SI units: Identify what 'lux' measures. Lux is defined as luminous flux incident per unit area in photometry; it quantifies how brightly a surface is illuminated. Choose the correct option.
IIT JEE
Physics
Difficulty: Easy
Choose an option
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AIlluminance (luminous flux per unit area)
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BLuminous intensity
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CLuminous flux
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DRadiant energy
Answer
Correct Answer: Illuminance (luminous flux per unit area)
Explanation
Given data
- Unit mentioned: lux.
ConceptIn SI, lux (lx) is the unit of illuminance, equal to 1 lumen per square metre (1 lx = 1 lm·m−2).
Common pitfallsConfusing illuminance (lux) with luminous intensity (candela) or luminous flux (lumen).
Final AnswerIlluminance (luminous flux per unit area)