Which of the following materials is typically used as an insulator?

Rubber is commonly used as an insulator due to its molecular structure, which contains tightly bound electrons. This structure prevents the flow of electric current, making it an effective barrier against electricity. Rubber’s insulating properties are utilized in various applications, including electrical wiring and protective gear, where it helps to minimize the risk of electrical shock and enables safe handling of electrical devices.

In contrast, materials like copper and silver are conductors, which allow the flow of electric current, and steel, while it has some insulating properties, does not provide the same level of effectiveness as rubber in preventing electrical conduction. Therefore, rubber stands out as the typical choice for insulation in various electrical and safety applications.