Unit 5 - Practice Quiz

1 In the classical free electron theory, the valence electrons in a metal are treated as:

2 What is the primary failure of the classical free electron theory (Drude-Lorentz theory)?

3 The Fermi energy () is defined as:

4 According to the Fermi-Dirac distribution function, what is the probability of occupation of an energy state at any temperature ?

5 Which of the following expressions represents the Fermi-Dirac distribution function?

6 Drift current in a semiconductor is caused by:

7 Diffusion current in a semiconductor flows from:

8 The relation between the diffusion coefficient () and mobility () is given by the Einstein relation:

9 In the band theory of solids, the formation of energy bands is primarily due to:

10 The energy gap () represents:

11 Which of the following characterizes an insulator?

12 The effective mass () of an electron in a solid is related to the curvature of the curve by:

13 If the curvature of the band () is negative near the top of the valence band, the effective mass is:

14 A 'hole' in solid state physics is best described as:

15 The Hall Effect is observed when a current-carrying conductor is placed in:

16 The Hall Coefficient () is defined mathematically as:

17 For an n-type semiconductor, the Hall coefficient is:

18 The formula for Hall coefficient in terms of carrier concentration is:

19 Which of the following parameters cannot be determined directly using the Hall Effect?

20 In the derivation of the Hall voltage , the Hall field exerts a force that balances the:

21 If the Hall voltage is , width of the specimen is , and thickness is , the Hall field is:

22 An intrinsic semiconductor at 0 K behaves as:

23 The Fermi level in an intrinsic semiconductor at absolute zero is located:

24 When a pentavalent impurity is added to pure silicon, the resulting semiconductor is:

25 In an N-type semiconductor, the donor energy level is located:

26 In a P-type semiconductor, the Fermi level moves:

27 The Law of Mass Action for semiconductors states that at equilibrium:

28 As the temperature of an extrinsic semiconductor increases significantly, the Fermi level:

29 The total conductivity () of a semiconductor is given by:

30 What is the primary difference between Direct and Indirect band gap semiconductors?

31 In a Direct Band Gap semiconductor, electron recombination results primarily in:

32 Which of the following is an example of an Indirect Band Gap semiconductor?

33 Why is Silicon not used for making LEDs?

34 The basic principle of a Solar Cell is:

35 The I-V characteristic of a solar cell is typically drawn in which quadrant?

36 The 'Fill Factor' of a solar cell represents:

37 In the Fermi-Dirac distribution, if and , then is:

38 The density of states for free electrons in a 3D metal is proportional to:

39 Which velocity is associated with the random motion of electrons at Fermi level?

40 In a p-n junction solar cell, electron-hole pairs are generated primarily in:

41 The efficiency of a solar cell is defined as:

42 For a p-type semiconductor, the concentration of holes () relates to the acceptor concentration () approximately as:

43 The mean free path of an electron is:

44 Mobility () of a charge carrier is defined as:

45 The unit of Hall coefficient () is:

46 What happens to the resistivity of a semiconductor as temperature increases?

47 In the Kronig-Penney model (origin of bands), the potential is approximated as:

48 Which material is commonly used as a dopant to create P-type Silicon?

49 The open-circuit voltage () of a solar cell:

50 If the effective mass of an electron is usually denoted , and the free electron mass is , in most semiconductors: