Band thoery

Question 1

Conduction Band

Answer 1

It is the lowest unfilled band

Question 2

Valence Band

Answer 2

It is the uppermost Band

Question 3

Forbidden Band

Answer 3

It is a range of energies which cannot be occupied bu an electron

Question 4

Intrinsic Semiconductors

Answer 4

It is a substance Such as pure silicon or germanium that at room temperature has a typical resistance between that of metals and insulators

Question 5

Intrinsic semiconductors at 0Kelvin

Answer 5

Valence band is fully occupied
The conduction band is empty
The forbidden band has a width of about 1eV

Question 6

Conduction in a metal

Answer 6

The valence band overlaps the conduction band

Forbidden band does not exist

Question 7

Conduction in insulators

Answer 7

The valence band is fully occupied
Conduction band is empty
Forbidden band is very wide

Question 8

LDR

Answer 8

Photons of light promote electrons from the valence band to conduction band by transferring their energy to electron
Increase in light intensity gives rise to an increase in the number of photons per unit time
Resistance decreases as the intensity of light increases