The relative luminosity for a wavelength of 600 nm is 0.6 . Determine the radiant flux at 600 nm required to generate the same brightness sensation as that produced by a radiant flux of 120 W at 555 nm .

Step-by-step solution

Luminous flux is given by the product of a constant, relative luminosity, and radiant flux. For the same brightness sensation, the luminous flux must be equal for both wavelengths. Let the radiant flux at 600 nm be . The relative luminosity at 555 nm is 1 (maximum). Equating the luminous flux for both wavelengths: V(600 nm ) = V(555 nm ) 120 0.6 = 1 120 = 120 0.6 = 200 W