Chapter 29, Problem 57A

To determine

To explain: Which one among the following materials would make the best insulator:

1. Forbidden gap $\text{8 eV}$ wide.
2. Forbidden gap $\text{3 eV}$ wide.
3. No forbidden gap.

Explanation of Solution

Introduction:

The forbidden gap of an insulator is greater than the forbidden gap of a conductor and semiconductor.

In an insulator the lowest energy level in the conduction band is $\text{5-10 eV}$ . Among of all the three options mentioned above, the material with a forbidden gap of $\text{8 eV}$ wide will make the best insulator as wider the gap is the better is the insulator. Insulators have a very wide forbidden gap; it does not conduct electricity.

Conclusion:

Hence among of all the three options, the material with a forbidden gap of $\text{8 eV}$ wide will make the best insulator