A thermal engineer is testing materials for a spacecraft's radiator panel. Two identical aluminium plates are prepared: Plate A is coated with a matte black thermal control paint, and Plate B is highly polished to a mirror-like finish. Both plates are electrically heated from behind so they are maintained at a constant, uniform temperature of 350 K350\text{ K}350 K in a vacuum chamber. An infrared radiometer is placed at an equal distance from the front face of each plate.
Despite both plates being at the exact same temperature, the radiometer measures a significantly higher intensity of infrared radiation from Plate A than from Plate B.
Explain why the radiometer records a higher reading for Plate A.