• # question_answer           Intensity of radiation at a surface in perpendicular direction is equal to: A) Product of emissivity of surface and $1/\pi .$B) Product of emissivity of surface and $\pi .$C) Product of emissive power of surface and $1/\pi .$D) Product of emissive power of surface and $\pi .$

Intensity of radiation, $I=E/\pi$