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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. 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

2 / 95

2. 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.

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

4 / 95

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

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

6 / 95

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

7 / 95

7. The core in a transformer provides ?

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8. Voltmeter draws ........................ current

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

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

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

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

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13. The most versatile circuit configuration for transistors is the

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14. A transformer consists of two inductive coils namely;

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

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

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17. 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

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

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

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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.

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21. A inductor stores energy in its _________

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

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23. 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

24 / 95

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

25 / 95

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

26 / 95

26. 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.

27 / 95

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

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28. A capacitor stores charge and hence, electric energy

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29. 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

30 / 95

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

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

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

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33. Calculate Rth, Vth, and I5

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

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35. A hole can also be described as a _________

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

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

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

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

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40. The collector current is determined by the _________

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41. A multiplier measures .................., ....................... and .....................

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

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

44 / 95

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

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45. ________ converts alternating currents into direct currents

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

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

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48. 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.

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

50 / 95

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

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

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

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

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

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55. No electrons can stay in the forbidden gap because

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

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57. 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

58 / 95

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

59 / 95

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

60 / 95

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

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61. 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.

62 / 95

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

63 / 95

63. A p-n junction is also known as

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

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

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

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67. Copper loss is usually larger than other losses

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68. Which of this is true

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69.

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

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70. What are the examples of passive elements?

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71. Calculate the equivalent resistance

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

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73. The transistor is a current __________ device.

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

75 / 95

75. 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)

76 / 95

76. 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 ___________

77 / 95

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

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78. Inductors smoothen sharp sudden changes in ..........

79 / 95

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

80 / 95

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

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

82 / 95

82. 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.

 

83 / 95

83. 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.

84 / 95

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

85 / 95

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

86 / 95

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

87 / 95

87. Inductors are very common in high-frequency circuit

88 / 95

88. Calculate Ia, Ib and Ic

89 / 95

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

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

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

92 / 95

92. Calculate the current flowing in the circuit

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

94 / 95

94. What type of bonds exist in semiconductors

95 / 95

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

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