A student investigates how different surfaces affect the emission of infrared radiation. They fill a metal Leslie's cube with hot water so that all four vertical sides are at the exact same temperature. One side is painted matt black, and another side is shiny silver. An infrared detector is placed at an equal distance from each surface.
Even though the temperature of each surface is the same, the infrared detector gives a different reading for each surface.
Give a reason why the detector records different readings for the different surfaces.