in a pure semiconductor, the number of electrons in the conduction band is
Answer Details
In a pure semiconductor, the number of electrons in the conduction band is equal to the number of holes in the valence band. A semiconductor has a valence band and a conduction band separated by a bandgap. The valence band is the highest energy band that is fully occupied by electrons, while the conduction band is the lowest energy band that is not occupied by electrons. In a pure semiconductor at absolute zero temperature, all electrons occupy the valence band and there are no electrons in the conduction band. As the temperature increases, some electrons gain enough energy to overcome the bandgap and transition from the valence band to the conduction band. This creates holes in the valence band, which are vacancies left by the electrons that have transitioned to the conduction band. The number of electrons in the conduction band is therefore equal to the number of holes in the valence band. Therefore, the correct option is: equal to the number of holes in the valence band.