The forbidden gap in the energy bands of Germanium at room temperature is about.

Hint: We know that germanium is a semiconductor hence it is obvious that it would have forbidden energy band gaps. However, we must remember that forbidden energy band gaps cannot be negative. To solve these types of questions we must know the proper definition of forbidden energy band gaps.

Complete step-by-step solution:
To solve this question let us first understand what a forbidden energy band gap means. Forbidden energy band gaps can be defined as the energy gap existing between the valence and the conduction band. We know that there are three types of materials: conductors, insulators and semiconductors. Semiconductors are those materials which have a forbidden energy band gap somewhere between the insulators and conductors. Also, they are capable of acting as conductors when an external electric field acts on them. Since germanium falls under the category of semiconductors it would also have a forbidden energy band gap. Usually, the forbidden energy band gap for germanium at room temperature is about \[0.7\text{ eV}\]. Generally, the forbidden energy band gap in the semiconductors is about \[1\text{ eV}\]. The conductivity of germanium at room temperature is low but with an increase in temperature its conductivity would increase. Although with an increase in temperature its forbidden energy band gap would decrease.

Note: We must keep in mind that the forbidden energy band gap for semiconductors depends on temperature hence we can conclude that as the temperature changes the energy bandgap will also change. It also depends on the structure of the crystal of the semiconductor.