Consider three different solids. There is a filled valence band in each, and the
ID: 1613036 • Letter: C
Question
Consider three different solids. There is a filled valence band in each, and then a gap, and then a band that is essentially empty. In solid A, the gap is essentially zero. In solid B the gap is about 2 eV. In solid C, the gap is about 10 eV. How would you classify these solids with respect to electrical conductivity.
1. A is a semiconductor, B is a conductor and C is an insulator.
2. A is a glass, B is a metal and C is a crystal like quartz.
3. A is a conductor, B is a semiconductor and C is an insulator.
4. A is an insulator, B is a conductor and C is a semiconductor.
5. A is a semiconductor, B is an insulator and C is a conductor.
Explanation / Answer
Solid A is a conductor as band gap is zero. Eletrons can freely move when an electric field is applied.
Solid B is a semiconductor as the elctrons, if provided thermal energy, can jump to the empty band and conduct electricity as the band gap is not too large.
Solid C is an insulator as the band gap is large and electrons won't be able to conduct electricity even if enough thermal energy is provided and electric field is applied as the gap is too large for the electrons to go to the empty band and conduct electricity.
So option 3 is correct.
***************************************************************************************************
This concludes the answers. Check the answer and let me know if it's correct. If you need any more clarification or correction, feel free to ask.....