Question

SI unit of luminance is given by 
1. candela/meter
2. candela meter
3. candela/meter²
4. candela² meter

Answer 1

Correct Answer - Option 3 : candela/meter²

CONCEPT:

Photometry: 

• Measurement of light as perceived by the human eye is called photometry.
• Main quantities of photometry are:
  • The luminous intensity of the source. Its SI unit is the candela (cd).
  • Luminous flux from the source
  • The illuminance of the surface
• Luminance is used to characterize the brightness of emitting or reflecting flat surfaces. 

EXPLANATION:

• Mathematically, luminance is luminous intensity per unit area.
  \(\rm \Rightarrow Luminance (L) = \dfrac{Intensity}{Area}= \dfrac{cd}{m^2}\)
• SI of luminance is candela/meter2 (cd/m2).