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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. Extrinsic semiconductors have more current conducting capacity than intrinsic semiconductors

2 / 95

2. 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.

 

3 / 95

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

4 / 95

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

5 / 95

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

6 / 95

6.

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

7 / 95

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

8 / 95

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

9 / 95

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

10 / 95

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

11 / 95

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

12 / 95

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

13 / 95

13. Which of this is true

14 / 95

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

15 / 95

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

16 / 95

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

17 / 95

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

18 / 95

18. What are the examples of passive elements?

19 / 95

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

20 / 95

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

21 / 95

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

22 / 95

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

23 / 95

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

24 / 95

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

25 / 95

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

26 / 95

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

27 / 95

27. 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.

28 / 95

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

29 / 95

29. Inductors are very common in high-frequency circuit

30 / 95

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

31 / 95

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

32 / 95

32. The transistor is a current __________ device.

33 / 95

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

34 / 95

34. Voltmeter draws ........................ current

35 / 95

35. 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)

36 / 95

36. A transformer consists of two inductive coils namely;

37 / 95

37. No electrons can stay in the forbidden gap because

38 / 95

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

39 / 95

39. Copper loss is usually larger than other losses

40 / 95

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

41 / 95

41. ________ converts alternating currents into direct currents

42 / 95

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

43 / 95

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

44 / 95

44. 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.

45 / 95

45. Calculate the current flowing in the circuit

46 / 95

46. The core in a transformer provides ?

47 / 95

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

48 / 95

48. A p-n junction is also known as

49 / 95

49. A hole can also be described as a _________

50 / 95

50. 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.

51 / 95

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

52 / 95

52. Calculate the equivalent resistance

53 / 95

53. Calculate Ia, Ib and Ic

54 / 95

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

55 / 95

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

56 / 95

56. A inductor stores energy in its _________

57 / 95

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

58 / 95

58. 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 ___________

59 / 95

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

60 / 95

60. 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.

61 / 95

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

62 / 95

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

63 / 95

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

64 / 95

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

65 / 95

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

66 / 95

66. 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.

67 / 95

67. 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

68 / 95

68. A multiplier measures .................., ....................... and .....................

69 / 95

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

70 / 95

70. 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

71 / 95

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

72 / 95

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

73 / 95

73. The most versatile circuit configuration for transistors is the

74 / 95

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

75 / 95

75. What type of bonds exist in semiconductors

76 / 95

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

77 / 95

77. 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

78 / 95

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

79 / 95

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

80 / 95

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

81 / 95

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

82 / 95

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

83 / 95

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

84 / 95

84. A capacitor stores charge and hence, electric energy

85 / 95

85. 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

86 / 95

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

87 / 95

87. Inductors smoothen sharp sudden changes in ..........

88 / 95

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

89 / 95

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

90 / 95

90. Calculate Rth, Vth, and I5

91 / 95

91. 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

92 / 95

92. The collector current is determined by the _________

93 / 95

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

94 / 95

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

95 / 95

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

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