A floodlight of radiant intensity shines on a sloped roof surface away

PHYSICS · Subjective · Fermi University Physics · Optics & Photonics · Geometrical optics and imaging · Geometrical optics and imaging

Optics and Photonics, Ch Radiometry and photometry

Problem

A floodlight of radiant intensity

I_\Omega = 200\ \mathrm{W\,sr^{-1}}

shines on a sloped roof surface

6.0\ \mathrm{m}

away, small enough compared with this distance to be treated as a point source. The roof's normal makes an angle of

55^\circ

with the line from the floodlight to the roof. Find the irradiance on the roof.