👉 The term "emissivity" is a measure of the transparency or opacity of a material. It represents how much light it blocks when reflected from an object. In other words, it's like how many different colors of light are blocked by a piece of cloth. For example, if you have a piece of cloth that has a high emissivity, it will reflect more light than some materials with a lower emissivity, and vice versa. This property is used in many applications, including solar panels