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Category: PHY 203 QUIZ

Some questions on the physics of active devices based on class jottings

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Created by Oluwaferanmi Akinyele

PHY 203 Quiz

These are likely questions for our test based on our class notes, few questions our lecturers asked in class, examples in the notes and some online questions.

 

This quiz consists of 95 questions covering all the topics we have been taught in PHY 203 till present. I hope we all find it helpful.

You have 50 mins for this quiz.

 

 

 

Contributors: Zainab, Verah & Lammylex (CHM department)

and Shukroh, Great Blakky and Ebun (PHY department)

 

Goodluck!❀

1 / 95

1. when the sensitivity of a meter is high, it means the meter has .............

2 / 95

2. A variable resistor in an electric circuit is for ...............

3 / 95

3. Which of the following is true about the effect of temperature on semiconductors

I. At absolute zero, there are no free electrons.

II. Above absolute zero, bonds break and electrons move under the influence of the applied electric field.

III. The semiconductor has its highest conductivity at absolute zero

IV. The semiconductor behaves as a perfect insulator at absolute zero

4 / 95

4. In a multimeter, when the variable resistance and the fixed resistance are connected in series with the battery and galvanometer, the multimeter functions as

5 / 95

5. To convert a multiplier to an ammeter, a .......... resistance is connected in .................. with a galvanometer

6 / 95

6. In pure inductors, current ......... the voltage by ......

7 / 95

7.

How many branches, nodes, loop and mesh do we have here?

8 / 95

8. Which of the following is/are correct?

I. Bipolar junction transistors control the current by varying the number of charge carriers

II. Voltage between 2 terminals are indicated by repeated letters

III. The emitter is lightly doped to reduce junction capacitance

IV. The emitter-base junction is forward biased

9 / 95

9. Inductors smoothen sharp sudden changes in ..........

10 / 95

10. Copper loss is usually larger than other losses

11 / 95

11. On the basis of their use, transformers are classified as

12 / 95

12. A capacitor stores charge and hence, electric energy

13 / 95

13. A transformer only increases the voltage with corresponding increase in current

14 / 95

14. Select the correct options only

I. Pentavalent impurities provide large number of free electrons to the semiconductor.

II. Trivalent impurities provide large number of free electrons to the semiconductor.

III. Trivalent impurities provide large number of holes to the semiconductor.

IV. Pentavalent impurities provide large number of holes to the semiconductor.

15 / 95

15. The arrangement of atoms in a repetitive manner is known as

16 / 95

16. A transformer consists of two inductive coils namely;

17 / 95

17. Extrinsic semiconductors have more current conducting capacity than intrinsic semiconductors

18 / 95

18. The majority carriers in an n-type semiconductor is ?

19 / 95

19. Which of the following is/are true

I. Reverse biasing prevents the flow of charge carriers across the junction.

II. Forward biasing is created when the positive terminal is connected to the n-type part of the PN junction.

III. In practice, when we apply reverse biasing to a PN junction, all the charge carriers stops to flow.

20 / 95

20. If a circuit has the following parameters Vcc =20V, Rs +Rm = 9.3KΩ, Vbe = 0.7, Im =1mA, and Β = 100. Calculate the meter current when E =10V and the voltmeter input r with or without the transistor.

21 / 95

21. Which of the following is correct

I. Small changes in V(BE) will produce large current changes in I(C) & I(E)

II. Small changes in V(CE) have little effect on I(B)

III. Small changes in V(CE) will produce large current changes in I(C) & I(E)

I, II, III & IVIV. Small changes in V(BE) will produce large current changes in I(B)

22 / 95

22. Any transistor designed must operate in the ________ region of the characteristic curve

23 / 95

23. Which of this must be connected to multimeter to be able to measure AC voltages?

24 / 95

24. Which of the statements about PN junction is true

I. A PN junction presents a high resistance if forward biased.

II. A PN junction presents a high resistance if reversed biased.

III A PN junction presents a low resistance if forward biased.

IV. A PN junction presents a low resistance if reversed biased.

 

25 / 95

25. A material that releases an electron from the valence band into the conduction band when a photon of light is incident on it is a ___________

26 / 95

26. Which of the following is true about transformers?

I. Open circuit test are done with a load on the transformer.

II. Copper loss is due to the ohmic resistance of the transformer windings.

III. Open circuit test is done to determine the 'no load loss' of the transformer.

IV. A transformer is electrically linked.

27 / 95

27. The emf that gets induced in the secondary winding according to Faraday's law of electromagnetic induction is called?

28 / 95

28. Circuit elements are connected in parallel when a common ................ is applied to each elements

29 / 95

29. When a small amount of trivalent impurity is added to a pure semi conductor, the semi conductor becomes

30 / 95

30. A resistor is regarded as a circuit element which puts energy into a circuit

31 / 95

31. Calculate Rth, Vth, and I5

32 / 95

32. In checking for continuity of circuit which on these is used

33 / 95

33. A meter is protected in the case of accidental workload by connecting ............... in .............. with a voltmeter

34 / 95

34. p-type and n-type semiconductor join together to form a ................. known as ................

35 / 95

35. An ammeter also detects the direction of the flow of current

36 / 95

36. In a RC circuit, voltage across the resistor ................... exponentially with time

37 / 95

37. A capacitor and an Inductor in an AC circuit is referred to as

38 / 95

38. ________ converts alternating currents into direct currents

39 / 95

39. The transistor is a three-terminal device that we can use to form a _____________ circuit

40 / 95

40. In an RL circuit voltage across the resistor increases exponentially

41 / 95

41. The separation between conduction band and valence band on the energy level diagram is called ________

42 / 95

42. The principle behind the working of a transformer is _________

43 / 95

43. Circuit elements connected in series have common ................. passing through each element

44 / 95

44. What is the number of branches, nodes, loops, and meshes?

45 / 95

45. A perfect amplifier has all of the following properties except:

46 / 95

46. In a transformer, most flux which get linked to the secondary winding is called?

47 / 95

47. Calculate the current flowing in the circuit

48 / 95

48. What type of bonds exist in semiconductors

49 / 95

49. Calculate the equivalent resistance

50 / 95

50. A capacitor C and an Inductor L store................. and .................... respectively

51 / 95

51. What are the examples of passive elements?

52 / 95

52. Why is a laminated steel core used in a transformer instead of a solid core?

53 / 95

53. The resistivity of a semiconductor is .......... that of an insulator, and ............that of conductors

54 / 95

54. A p-n junction is also known as

55 / 95

55. The collector current is determined by the _________

56 / 95

56. Which of the following transformers has a high rating?

57 / 95

57. Inductors are very common in high-frequency circuit

58 / 95

58. ...................... are responsible for the conduction  in a conductor

59 / 95

59. The loss due to the reversal of magnetization in the transformer core is known as

60 / 95

60. A component that allows the flow of current in only one direction is called ..........

61 / 95

61. A 6600/550V, 25KVA transformer has iron losses of 350W and its 1Âș and 2° winding resistances are 14.5 and 0.1Ω respectively. Determine the full load efficiency at a power factor of unity.

62 / 95

62. An Inductor tend to smooth sudden change in .................

63 / 95

63. A emitter-follower circuit has Vcc =12V, Rm = 1KΩ and a 2mA meter. If the amplification factor of the resistor is 80 and Vbe = 0.7. Calculate the suitable r for Rs to give fsd when E= 5V.

64 / 95

64. What is known as eddy current loss in a transformer?

65 / 95

65. Coils are ............... separated, but ................ linked together

66 / 95

66. A semiconductor in an extremely pure form is known as .............

67 / 95

67. The Norton's equivalent circuit contains a Norton equivalent source "I(N)" in parallel with an equivalent resistor R(N)

68 / 95

68. A hole can also be described as a _________

69 / 95

69. Depletion layer serves as barrier to the movement of free electrons.

70 / 95

70. The potential barrier of a P-N junction depends on which of the following except

71 / 95

71. A galvanometer measures and detects extremely small currents both in ..................... and ...........................

72 / 95

72. The voltage signal at the collector is out of phase with the signal at the base by:

73 / 95

73. No electrons can stay in the forbidden gap because

74 / 95

74. The transistor is a current __________ device.

75 / 95

75. In a semiconductor, as temperature increases, conductivity ..................

76 / 95

76. A mesh is any closed path in a circuit which does not enclose any other closed path inside it

77 / 95

77. Loading effect of a meter happens because...............

78 / 95

78. AC Current and Voltage may vary with time. True or False?

79 / 95

79. Voltmeter draws ........................ current

80 / 95

80. A node is a collection point for two or more banches

81 / 95

81. Which of these will result in forward biasing

I. when certain dc voltage is applied to the junction in such a direction that it cancels the potential barrier thus permitting the flow of current

II. Connecting the negative terminal of the battery to the p-type and positive terminal to the n-type

III. Connecting the positive terminal of the battery to the p-type and negative terminal to the n-type

IV. when certain dc voltage is applied to the junction in such a direction that the potential barrier is increased

82 / 95

82. The core in a transformer provides ?

83 / 95

83. A Thevenin's equivalent circuit contains an equivalent source Vth in parallel with an equivalent resistor Rth

84 / 95

84. The e–h+ pair can also be called ____

85 / 95

85. The loss due to ohmic resistance of the transformer windings

86 / 95

86. The process of setting up a current to operate a transistor at a desired point on its characteristic curve is known as __________

87 / 95

87. A inductor stores energy in its _________

88 / 95

88. In electronics, _____ refers to the use of DC voltage to establish certain operating conditions for an electronic device.

89 / 95

89. Which of this is true

90 / 95

90. The most versatile circuit configuration for transistors is the

91 / 95

91. A laminated steel core that has high silicon content provides

92 / 95

92. Calculate Ia, Ib and Ic

93 / 95

93. A multiplier measures .................., ....................... and .....................

94 / 95

94. Which of the following statements is/are true? I. A multimeter can be used as an ammeter when low resistance is connected in parallel with the galvanometer II. A low sensitive meter will measure Voltage perfectly III. A multimeter cannot be used to determine circuit continuity IV. A multimeter can be used as an voltmeter when high resistance is connected in series with the galvanometer

95 / 95

95. Consider the following statements and choose only correct answers

I. The resistivity of a semiconductor is less than that of an insulator and more than a conductor

II. As temperature increases, the conductivity of semiconductors decreases

III. We can consider a semiconductor as a resistance material

IV. Semiconductors have a negative temperature coefficient of resistance

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