Topic Outline
- MCQs in Conductors
- MCQs in Semiconductors
- MCQs in Silicon Crystal
- MCQs in Intrinsic Semiconductors
- MCQs in Two Types of Flow
- MCQs in Doping Semiconductors
- MCQs in Two types of Extrinsic Semiconductors
- MCQs in the Unbiased Diode
- MCQs in Energy Levels
- MCQs in Reversed-Biased Diode
Start Practice Exam Test Questions
Choose the letter of the best answer in each questions.
1. The nucleus of a copper atom contains how many protons?
- a. 1
- b. 4
- c. 18
- d. 29
2. The net charge of a neutral copper atom is
- a. 0
- b. +1
- c. -1
- d. +4
3. Assume the valence electron is removed from a copper atom. The net charge of the atom becomes
- a. 0
- b. + 1
- c. -1
- d. +4
4. The valence electron of a copper atom experiences what kind of attraction toward the nucleus?
- a. None
- b. Weak
- c. Strong
- d. Impossible to say
5. How many valence electrons does a silicon atom have?
- a. 0
- b. 1
- c. 2
- d. 4
6. Which is the most widely used semiconductor?
- a. Copper
- b. Germanium
- c. Silicon
- d. None of the above
7. How many protons does the nucleus of a silicon atom contain?
- a. 4
- b. 14
- c. 29
- d. 32
8. Silicon atoms combine into an orderly pattern called a
- a. Covalent bond
- b. Crystal
- c. Semiconductor
- d. Valence orbit
9. An intrinsic semiconductor has some holes in it at room temperature. What causes these holes?
- a. Doping
- b. Free electrons
- c. Thermal energy
- d. Valence electrons
10. Each valence electron in an intrinsic semiconductor establishes a
- a. Covalent bond
- b. Free electron
- c. Hole
- d. Recombination
11. The merging of a free electron and a hole is called
- a. Covalent bonding
- b. Lifetime
- c. Recombination
- d. Thermal energy
12. At room temperature an intrinsic silicon crystal acts approximately like
- a. A battery
- b. A conductor
- c. An insulator
- d. A piece of copper wire
13. The amount of time between the creation of a hole and its disappearance is called
- a. Doping
- b. Lifetime
- c. Recombination
- d. Valence
14. The valence electron of a conductor is also called a
- a. Bound electron
- b. Free electron
- c. Nucleus
- d. Proton
15. A conductor has how many types of flow?
- a. 1
- b, 2
- c. 3
- d. 4
16. A semiconductor has how many types of flow?
- a. 1
- b. 2
- c. 3
- d. 4
17. When a voltage is applied to a semiconductor, holes will flow
- a. Away from the negative potential
- b. Toward the positive potential
- c. In the external circuit
- d. None of the above
18. A conductor has how many holes?
- a. Many
- b. None
- c. Only those produced by thermal energy
- d. The same number as free electrons
19. In an intrinsic semiconductor, the number of free electrons
- a. Equals the number of holes
- b. Is greater than the number of holes
- c. Is less than the number of holes
- d. None of the above
20. Absolute zero temperature equals
- a. -273 degrees C
- b. 0 degrees C
- c. 25 degrees C
- d. 50 degrees C
21. At absolute zero temperature an intrinsic semiconductor has
- a. A few free electrons
- b. Many holes
- c. Many free electrons
- d. No holes or free electrons
22. At room temperature an intrinsic semiconductor has
- a. A few free electrons and holes
- b. Many holes
- c. Many free electrons
- d. No holes
23. The number of free electrons and holes in an intrinsic semiconductor increases when the temperature
- a. Decreases
- b. Increases
- c. Stays the same
- d. None of the above
24. The flow of valence electrons to the left means that holes are flowing to the
- a. Left
- b. Right
- c. Either way
- d. None of the above
25. Holes act like
- a. Atoms
- b. Crystals
- c. Negative charges
- d. Positive charges
26. Trivalent atoms have how many valence electrons?
- a. 1
- b. 3
- c. 4
- d. 5
27. A donor atom has how many valence electrons?
- a. 1
- b. 3
- c. 4
- d. 5
28. If you wanted to produce a p-type semiconductor, which of these would you use?
- a. Acceptor atoms
- b. Donor atoms
- c. Pentavalent impurity
- d. Silicon
29. Holes are the minority carriers in which type of semiconductor?
- a. Extrinsic
- b. Intrinsic
- c. n-type
- d. p-type
30. How many free electrons does a p-type semiconductor contain?
- a. Many
- b. None
- c. Only those produced by thermal energy
- d. Same number as holes
31. Silver is the best conductor. How many valence electrons do you think it has?
- a. 1
- b. 4
- c. 18
- d. 29
32. Suppose an intrinsic semiconductor has 1 billion free electrons at room temperature. If the temperature changes to 75'C, how many holes are there?
- a. Fewer than 1 billion
- b. 1 billion
- c. More than 1 billion
- d. Impossible to say
33. An external voltage source is applied to a p-type semiconductor. If the left end of the crystal is positive, which way do the majority carriers flow?
- a. Left
- b. Right
- c. Neither
- d. Impossible to say
34. Which of the following doesn't fit in the group?
- a. Conductor
- b. Semiconductor
- c. Four valence electrons
- d. Crystal structure
35. Which of the following is approximately equal to room temperature?
- a. 0 degrees C
- b. 25 degrees C
- c. 50 degrees C
- d. 75degrees C
36. How many electrons are there in the valence orbit of a silicon atom within a crystal?
- a. 1
- b. 4
- c. 8
- d. 14
37. Positive ions are atoms that have
- a. Gained a proton
- b. Lost a proton
- c. Gained an electron
- d. Lost an electron
38. Which of the following describes an n-type semiconductor?
- a. Neutral
- b. Positively charged
- c. Negatively charged
- d. Has many holes
39. A p-type semiconductor contains holes and
- a. Positive ions
- b. Negative ions
- c. Pentavalent atoms
- d. Donor atoms
40. Which of the following describes a p-type semiconductor?
- a. Neutral
- b. Positively charged
- c. Negatively charged
- d. Has many free electrons
41. Which of the following cannot move?
- a. Holes
- b. Free electrons
- C. Ions
- d. Majority carriers
42. What causes the depletion layer?
- a. Doping
- b. Recombination
- c. Barrier potential
- d. Ions
43. What is the barrier potential of a silicon diode at room temperature?
- a. 0.3 V
- b. 0.7 V
- C. 1 V
- d. 2 mV per degree Celsius
44. To produce a large forward current in a silicon diode, the applied voltage must be greater than
a. 0
b. 0.3 V
c. 0.7 V
d. 1 V
45. In a silicon diode the reverse current is usually
- a. Very small
- b. Very large
- c. Zero
- d. In the breakdown region
46. Surface-leakage current is part of the
- a. Forward current
- b. Forward breakdown
- c. Reverse current
- d. Reverse breakdown
47. The voltage where avalanche occurs is called the
- a. Barrier potential
- b. Depletion layer
- c. Knee voltage
- d. Breakdown voltage
48. Diffusion of free electrons across the junction of an unbiased diode produces
- a. Forward bias
- b. Reverse bias
- c. Breakdown
- d. The depletion layer
49. When the reverse voltage increases from 5 to 10 V, the depletion layer
- a. Becomes smaller
- b. Becomes larger
- c. Is unaffected
- d. Breaks down
- d. All of the above
50. When a diode is forward biased, the recombination of free electrons and holes may produce
- a. Heat
- b. Light
- c. Radiation
- d. All of the above
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