Which term refers to materials that do not allow electricity to pass through easily?

• A. Conductors
• B. Matter
• C. Elements
• D. Insulators

Answer: (D)

Electric current moves by the flow of electrons; materials that stop or resist that flow have tightly bound electrons and high resistance. An insulator is a material that does not let electricity pass through easily, which is why substances like rubber, plastic, and glass are used as coatings to keep electrical parts safe. In contrast, conductors have free-moving electrons and allow current to flow readily, like metals. The other terms are broader: matter is anything with mass and occupy space, and elements are pure substances that can be metals or nonmetals and may conduct or insulate depending on the substance. The term that precisely describes materials that resist electric flow is insulators.