Malvino Chapter 2 With Answers Electronics ECE Board Exam

Malvino Chapter 2 With Answers Electronics ECE Board Exam

Chapter 2

1. The nucleus of a copper atom contains how many protons?

a. 1

b. 4

c. 18

d. 29

d

2. The net charge of a neutral copper atom is

a. 0

b. +1

c. -1

d. +4

a

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

b

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

b

5. How many valence electrons does a silicon atom have?

a. 0

b. 1

c. 2

d. 4

d

6. Which is the most widely used semiconductor?

a. Copper

b. Germanium

c. Silicon

d. None of the above

c

7. How many protons does the nucleus of a silicon atom contain?

a. 4

b. 14

c. 29

d. 32

b

8. Silicon atoms combine into an orderly pattern called a

a. Covalent bond

b. Crystal

c. Semiconductor

d. Valence orbit

b

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

c

10. Each valence electron in an intrinsic semiconductor establishes a

a. Covalent bond

b. Free electron

c. Hole

d. Recombination

a

11. The merging of a free electron and a hole is called

a. Covalent bonding

b. Lifetime

c. Recommendation

d. Then-nal energy

c

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

c

13. The amount of time between the creation of a hole and its disappearance is called

a. Doping

b. Lifetime

c. Recombination

d. Valence

b

14. The valence electron of a conductor is also called a

a. Bound electron

b. Free electron

c. Nucleus

d. Proton

b

15. A conductor has how many types of flow?

a. 1

b, 2

c. 3

d. 4

a

16. A semiconductor has how many types of flow?

a. 1

b. 2

c. 3

d. 4

b

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

d

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

b

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

a

20. Absolute zero temperature equals

a. -273 degrees C

b. 0 degrees C

c. 25 degrees C

d. 50 degrees C

a

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

d

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

a

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

b

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

b

25. Holes act like

a. Atoms

b. Crystals

c. Negative charges

d. Positive charges

d

26. Trivatent atoms have how many valence electrons?

a. 1

b. 3

c. 4

d. 5

b

27. A donor atom has how many valence electrons?

a. 1

b. 3

c. 4

d. 5

d

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

a

29. Holes are the minority carriers in which type of semiconductor?

a. Extrinsic

b. Intrinsic

c. n-type

d. p-type

c

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

c

31. Silver is the best conductor.  How many valence electrons do you think it has?

a. 1

b. 4

c. 18

d. 29

a

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

c

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

b

34. Which of the following doesn't fit in the group?

a. Conductor

b. Semiconductor

c. Four valence electrons

d. Crystal structure

a

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

b

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

c

37. Positive ions are atoms that have

a. Gained a proton

b. Lost a proton

c. Gained an electron

d. Lost an electron

d

38. Which of the following describes an n-type semiconductor?

a. Neutral

b. Positively charged

c. Negatively charged

d. Has many holes

a

39. A p-type semiconductor contains holes and

a. Positive ions

b. Negative ions

c. Pentavalent atoms

d. Donor atoms

b

40. Which of the following describes a p-type semiconductor?

a. Neutral

b. Positively charged

c. Negatively charged

d. Has many free electrons

a

41. Which of the following cannot move?

a. Holes

b. Free electrons

C. Ions

d. Majority carriers

c

42. What causes the depletion layer?

a. Doping

b. Recombination

c. Barrier potential

d. Ions

b

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

b

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

c

45. In a silicon diode the reverse current is usually

a. Very small

b. Very large

c. Zero

d. In the breakdown region

a

46. Surface-leakage current is part of the

a. Forward current

b. Forward breakdown

c. Reverse current

d. Reverse breakdown

c

47. The voltage where avalanche occurs is called the

a. Barrier potential

b. Depletion layer

c. Knee voltage

d. Breakdown voltage

d

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

d

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

b

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

d