Free electrons in conductors etc. Help please! (1 Viewer)

[Bashy14]

Hey i need some help with the following dot point in the Ideas to Implementation syllabus.

"Compare qualitatively the relative number of free electrons that can drift from atom to atom in conductors semiconductors and insulators."

Any information that could help answer / explain / summarize that question would be awesome.

 

[IAU001]

• every atom in a conductor contributes valence electrons for conduction (abt 10^22 electrons per cubic cm of the conductor)
• semiconductors have about 10^15 electrons per cubic centremetre available for conduction
• Doped, n-type semiconductors have abt 100 times more electrons than pure semiconductors. but p-type semicondcutors, thoguh they hv less valence electrons, they have better conductivity coz of the positive holes
• there arent any free elctrons to form a current when voltage is applied acorss the ends of an insulator

hope tht helps =]