Definition: | quotient of the luminous flux Φv by the corresponding radiant flux Φe
X
unit: lm · W -1
NOTE – When applied to monochromatic radiations, the maximum value of K(λ) is denoted by the symbol Km.
Km = 683 lm • W -1 for vm = 540 x 1012 Hz (λm ≈ 555 nm) for photopic vision.
K'm = 1700 lm • W -1 for λ'm = 507 nm for scotopic vision.
For other wavelengths : K(λ) = Km V(λ) and K'(λ) = K'm V'(λ).
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