Physics – 2.3.3 Radiation | e-Consult

Surface Colour (Black vs. White):

Black surfaces are very effective emitters and absorbers of infrared radiation. This is because they absorb a large proportion of the incident infrared radiation, converting it into thermal energy. As a result, a black surface also emits a large amount of infrared radiation. White surfaces, on the other hand, are poor absorbers and poor emitters of infrared radiation. They reflect most of the incident infrared radiation. Therefore, a white surface absorbs less energy and emits less infrared radiation.

Surface Texture (Dull vs. Shiny):

A dull surface scatters infrared radiation in all directions. This means that a significant portion of the infrared radiation that hits the surface is reflected. A shiny surface, however, reflects infrared radiation in a more specular (directional) manner. While some infrared radiation is still absorbed, a greater proportion is reflected. The degree of reflection depends on the smoothness of the surface; a perfectly smooth surface will reflect more infrared radiation than a rough surface.

In summary: Black surfaces absorb and emit more infrared radiation, while white surfaces reflect and emit less. Dull surfaces reflect more infrared radiation than shiny surfaces.