What best describes materials that obstruct the flow of thermal energy?

Materials that obstruct the flow of thermal energy are known as insulators. Insulators are substances that do not conduct heat well, meaning they provide resistance to the transfer of thermal energy. This is because insulators have tightly bound electrons that do not move freely, limiting the ability to transfer heat through conduction. Common examples of insulators include materials like rubber, glass, and certain types of plastics, which are used in various applications to maintain temperatures.

In contrast, resistors are components that impede electrical flow and do not specifically relate to thermal energy flow. Conductors, on the other hand, are materials that allow for easy transfer of thermal energy, such as metals. Filters are used to block certain frequencies of waves, such as light or sound, and are not relevant to thermal energy conduction. Thus, insulators play a crucial role in applications needing temperature regulation by preventing heat loss or gain.