1. An intrinsic semiconductor is:
(A) Pure semiconductor
(B) Doped semiconductor
(C) Metal conductor
(D) Insulator
2. In an intrinsic semiconductor, the number of electrons is:
(A) Greater than holes
(B) Equal to holes
(C) Zero
(D) Infinite
3. The conductivity of an intrinsic semiconductor:
(A) Increases with temperature
(B) Decreases with temperature
(C) Remains constant
(D) Is zero
4. Silicon and germanium are examples of:
(A) Metals
(B) Insulators
(C) Intrinsic semiconductors
(D) Extrinsic semiconductors only
5. Extrinsic semiconductors are obtained by:
(A) Heating intrinsic semiconductors
(B) Doping intrinsic semiconductors
(C) Cooling metals
(D) Oxidation
6. N-type semiconductors are created by adding:
(A) Acceptor atoms
(B) Donor atoms
(C) Both acceptor and donor atoms
(D) Metal atoms only
7. P-type semiconductors are created by adding:
(A) Donor atoms
(B) Acceptor atoms
(C) Metal atoms
(D) Pure silicon
8. The majority carriers in N-type semiconductor are:
(A) Holes
(B) Electrons
(C) Ions
(D) Neutrons
9. The majority carriers in P-type semiconductor are:
(A) Electrons
(B) Holes
(C) Ions
(D) Neutrons
10. Doping a semiconductor increases:
(A) Band gap
(B) Electrical conductivity
(C) Thermal resistance
(D) Atomic mass
11. In N-type silicon, the donor atom is typically:
(A) Boron
(B) Phosphorus
(C) Gallium
(D) Indium
12. In P-type silicon, the acceptor atom is typically:
(A) Phosphorus
(B) Boron
(C) Arsenic
(D) Antimony
13. In intrinsic semiconductors, the Fermi level lies:
(A) Closer to conduction band
(B) Closer to valence band
(C) Midway between conduction and valence bands
(D) Outside the band gap
14. In N-type semiconductors, the Fermi level:
(A) Shifts closer to conduction band
(B) Shifts closer to valence band
(C) Remains at midpoint
(D) Shifts below valence band
15. In P-type semiconductors, the Fermi level:
(A) Shifts closer to conduction band
(B) Shifts closer to valence band
(C) Remains at midpoint
(D) Shifts above conduction band
16. Extrinsic semiconductors have:
(A) Only intrinsic carriers
(B) Additional carriers due to doping
(C) No carriers
(D) Infinite resistivity
17. In N-type material, minority carriers are:
(A) Electrons
(B) Holes
(C) Donor atoms
(D) Neutrons
18. In P-type material, minority carriers are:
(A) Holes
(B) Electrons
(C) Acceptors
(D) Protons
19. The conductivity of an extrinsic semiconductor is:
(A) Lower than intrinsic
(B) Higher than intrinsic
(C) Zero
(D) Infinite
20. The energy band gap of silicon is approximately:
(A) 0.7 eV
(B) 1.1 eV
(C) 1.5 eV
(D) 2.0 eV
21. The energy band gap of germanium is approximately:
(A) 0.66 eV
(B) 1.1 eV
(C) 1.5 eV
(D) 2.0 eV
22. Which type of carrier dominates conduction in intrinsic semiconductors at room temperature?
(A) Electrons
(B) Holes
(C) Both equally
(D) Ions
23. Extrinsic semiconductors are classified as:
(A) Only N-type
(B) Only P-type
(C) N-type or P-type
(D) Metallic
24. Doping concentration in extrinsic semiconductors is typically:
(A) 10^15 to 10^20 atoms/cm³
(B) 10^5 to 10^10 atoms/cm³
(C) 10^25 atoms/cm³
(D) 10^2 atoms/cm³
25. Minority carrier concentration in N-type material:
(A) Equal to majority carriers
(B) Much less than majority carriers
(C) Zero
(D) Infinite
26. Minority carrier concentration in P-type material:
(A) Equal to majority carriers
(B) Much less than majority carriers
(C) Zero
(D) Infinite
27. An intrinsic semiconductor at absolute zero behaves as:
(A) Conductor
(B) Insulator
(C) Semiconductor
(D) Superconductor
28. The electrical conductivity of intrinsic semiconductors depends on:
(A) Temperature only
(B) Doping only
(C) Both temperature and band gap
(D) Magnetic field
29. The mobility of electrons in semiconductors is:
(A) Higher than holes
(B) Lower than holes
(C) Equal to holes
(D) Zero
30. The main advantage of extrinsic semiconductors is:
(A) High mechanical strength
(B) Controlled conductivity
(C) No temperature dependence
(D) No band gap