|MLA Citation:||Bloomfield, Louis A. "Question 1033"|
How Everything Works 23 Apr 2018. 23 Apr 2018 <http://howeverythingworks.org/print1.php?QNum=1033>.
In a conductor, there are many unused levels available within easy reach of the electrons. If the electrons have to begin moving toward the left, in order to carry an electric current, some of the electrons that are in right-heading levels can shift into empty left-heading levels in order to let that current flow. But in an insulator, all of the easily accessible levels are filled and the electrons can't shift to other levels in order to carry current in a particular direction. While there are empty levels around, an electron would need a large increase in its energy to begin traveling in one of these empty levels. As a result, the electrons in an insulator can't carry an electric current.