DE LA SALLE UNIVERSITY - DASMARINASEngineering Department

Electronics Engineering Program

ELECTRONICS

Name: _______________________________ Course/Year/Section ______________ Score

TEST I. Choose the letter that corresponds to the correct answer on the space provided on the answer sheet.

1. A software use in robotics wherein it is capable of moving any single degree of freedom to any intermediate point between the two extreme positions.

a. point-to-stop software b. point-to-point softwarec. continuous-path software d. discreet-path software

2. Two inductors, each of 100 µH, are in series. The coefficient of coupling is 0.40. The net inductance, if the coil fields reinforce each other, is

a. 50 µH b. 120 µHc. 200 µH d. 280 µH

3. A charged point particle is placed at the center of a spherical Gaussian surface. The electric flux ϕE is changed if

a. the sphere is replaced by a cube of the same volumeb. the sphere is replaced by a cube of one-tenth the volumec. the point charge is moved off centerd. the point charge is moved to just outside the sphere

4. The peak value of the input to a half-wave rectifier is 10 V. The approximate peak value of the output is

a. 10.7 V b. 9.3 Vc. 10 V d. 3.18 V

5. A watt hour meter measures

General Direction:1. Use pencil number (2) only.2. Erasures in the final answers are considered incorrect.3. Use of cellular phone and programmable calculators are not allowed.4. Write all required answers and computations on the answer sheet provided.

a. Voltage b. Currentc. Power d. Energy

6. A connection of branches forming a closed-path passing through any node only once is called a

a. junction b. meshc. loop d. circuit

7. Let Q denote charge, V denote potential difference, and U denote stored energy. Of these quantities, capacitors in parallel must have the same:

a. Q only b. V onlyc. U only d. Q and U only

8. How many lines are there in the data bus?

a. 10 b. 6c. 8 d. 12

9. If the resistance of a capacitor-filtered full full-wave rectifier is reduced, the ripple voltage

a. is not affected b. increasesc. decreases d. has a different frequency

10. In a highly inductive circuit, a small capacitance is added in series. The phase difference between the voltage and current will

a. increase b. decreasec. remain the same d. slightly change

11. If the feedback fraction in an amplifier is 0.01, then gain with negative feedback is approximately _____.

a. 10 b. 100c. 1000 d. 500

12. An RLC circuit has a capacitance of 12 µF, an inductance of 25 mH, and a resistance of 60Ω. The current oscillates with an angular frequency of

a. 1.2 x 103 rad/s b. 1.4 x 103 rad/sc. 1.8 x 103 rad/s d. 2.2 x 103 rad/s

13. Which of the following is a condition when a transistor is operating in the active region?

a. IB = βIE b. IC = βIB

c. IC = IB d. IC = IE

14. An advantage of an alkaline cell over a zinc-carbon cell is that:

a. The alkaline cell provide more voltageb. The alkaline cell can be rechargedc. An alkaline cell works at lower temperaturesd. The alkaline cell is far less bulky for the same amount of energy capacity

15. When a PLL is locked on the input frequency, the VCO frequency

a. Is less than fo b. Is greater than fo

c. Equals fin d. Equals fo

16. The process of adding an impurity to an intrinsic semiconductor is called

a. atomic modification b. dopingc. recombination d. ionization

17. Which of the following motors requires both AC and DC power supplies to run it?

a. Universal motor b. Induction motorc. Synchronous motor d. Wound rotor motor

18. The majority carriers in an n-type semiconductor are

a. holes b. conduction electronsc. valence electron d. protons

19. A device commonly used for remote switching of wire communications signal is

a. A solenoid b. An electromagnetc. A potentiometer d. A photovoltaic cell

20. A student kept her 60-watt, 120-volt study lamp turned on from 2:00 PM until 2:00 AM. How many coulombs of charge went through it?

a. 150 b. 3,600c. 7,200 d. 21,600

21. A hydrogen atom that has lost its electron is moving east in a region where the magnetic field is directed from south to north. It will be deflected

a. up b. downc. north d. south

22. NICAD memory

a. Occurs often when NICADs are misusedb. Indicates that the cell or battery is deadc. Does not occur very oftend. Can cause a NICAD to explode

23. An RL circuit has an impedance of Z = 6 + j8 ohms. What is the susceptance?

a. 6 b. 0.01c. 8 d. 0.08

24. What type of voltage is induced in a loop of wire rotating in a strong and steady magnetic field?

a. Pulsating dc b. rectified acc. dc d. ac

25. When a 60 Hz sinusoidal voltage is applied to the input of a half-wave rectifier, the output frequency is

a. 60 Hz b. 120 Hzc. 0 Hz d. 30 Hz

26. Every chemical element has its own unique type of particle, called its

a. Molecule b. Electronc. Proton d. Atom

27. What is the most common impurity found in the battery electrolyte?

a. HCl b. Leadc. Iron d. Water

28. A megaohmmeter is usually designed for measuring which of the following?

a. Very high resistance b. ground faults in power linesc. Very low resistance d. Overloads on dc motors

29. Which of the following is TRUE about FET?

a. It has a forward biased PN junctionb. It has a very high input resistancec. It has a very low input resistanced. It has a high connection emitter junction

30. Static electricity is most often produced by which of the following?

a. Pressure b. Magnesiumc. Heat d. Friction

31. Which of the following is TRUE about a shift register?

a. It stores both serial and parallel datab. Converts serial data to parallelc. Converts parallel data to seriald. All of these

32. What circuit element used to resonate with capacitor?

a. resistors b. Transistorsc. Inductors d. Diodes

33. The average value of a half-wave rectified voltage with a peak value of 200 V is

a. 127.3 V b. 141 Vc. 0 V d. 63.7 V

34. An advantage of magnetic disk over magnetic tape for data storage is that

a. Data is too closely packed on the tapeb. The disk is immune to the effects of magnetic fieldsc. Data storage and retrieval is faster on diskd. Disks store computer data in analog form

35. The positive lead of an ohmmeter is connected to the anode of a diode and the negative lead is connected to the cathode. The diode is

a. reverse-biased b. forward-biasedc. open d. faulty

36. Primary cells

a. Can be used over and overb. Have higher voltage than other types of cellsc. All have exactly 1.500 Vd. Cannot be recharged

37. In order to show that a resistor has a tolerance of ±10%

a. The third band must be silverb. No color in the fourth band

c. The fourth band is goldd. The fourth band must be silver

38. A certain D-MOSFET is biased at VGS = 0 V. Its data sheet specifies IDSS = 20 mA and VGS(off)

= -5 V. The value of the drain current

a. is 0 A b. is 5 mAc. is 20 mA d. is 50 mA

39. Which of the following is similar to a de-multiplexer?

a. Decoder b. Data selectorc. Encoder d. Operator

40. An n-channel D-MOSFET with positive VGS is operating in

a. the depletion mode b. cutoffc. the enhancement mode d. saturation

41. Emitter follower is another name for what transistor configuration?

a. Common emitter b. Common basec. Common collector d. All of these

42. Why is the core of a transformer laminated?

a. To reduce the volume of core usedb. To reduce eddy lossc. To decrease the overall weight of the cored. To reduce the copper loss

43. A feature that distinguishes the J-K flip-flop from the S-R flip-flop is the

a. toggle condition b. preset inputc. type of clock d. clear input

44. At DC steady state, an inductor acts like which of the following?

a. an open circuit b. a capacitorc. a short circuit d. an insulator

45. A MOSFET is a special type of

a. JFET b. D-MOSFETc. E-MOSFET d. A and C

46. What will happen if the control system has an excessive noise on it?

a. Overall gain is reducedb. Bandwidth is reducedc. The system will oscillated. The amplifying stages will saturate

47. What is the angular velocity for a 25-cycle circuit?

a. 3.1416 radian per second b. 377 radian per secondc. 157 radian per second d. 314 radian per second

48. For a certain JFET, IGSS= 10 V. The input resistance is

a. 1 MΩ b. 1000 MΩc. 100 MΩ d. 1000 mΩ

49. Which of the following is TRUE about a signal flow graph?

a. It is a special type of graph for analysis of modern control system b. It is a semi-log graph c. It is a log-log graph d. It is a topological representation of asset of differential equation

50. What is the name of resistance wire wrapped around an insulating core?

a. Film-type b. Carbon compositionc. Fusible type d. Wire wound

51. The magnitude of the charge on an electron is approximately

a. 1023 C b. 10-23 Cc. 1019 C d. 10-19 C

52. A silicon diode is in series with 1.0 kΩ resistor and a 5 V battery. If the anode is connected to the positive battery terminal, the cathode voltage with respect to the negative battery terminal is

a. 0.7 V b. 5.7 Vc. 0.3 V d. 4.3 V

53. The total negative charge on the electrons in 1 mol of helium (atomic number 2, molar mass 4) is

a. 4.8 x 104 C b. 9.6 x 104 Cc. 1.9 x 105 C d. 3.8 x 105 C

54. A rheostat

a. Is used in high-voltage and/or high-power dc circuitsb. Is ideal for tuning a radio receiver c. Is often used as a bleeder resistord. Is better than a potentiometer for low-power audio

55. A particle with a charge of 5 x 10-6 C and a mass of 20 g moves uniformly with a speed of 7 m/s in a circular orbit around a stationary particle with a charge of -5 x 10 -6 C. The radius of the orbit is:

a. 0 m b. 0.23 mc. 0.62 m d. 1.6 m

56. The purpose of a pentavalent impurity is to

a. increase the number of free electronsb. create minority carriersc. reduce the conductivity of silicond. increase the number of holes

57. A material with high permeability

a. increases magnetic field quantityb. is necessary if a coil is to produce a magnetic fieldc. always has high retentivityd. concentrates magnetic lines of flux58. Charge is distributed uniformly on the surface of a spherical balloon (an insulator). A point particle with charge q is inside. The electrical force on the particle is greatest when

a. it is near the inside surface of the balloonb. it is at the center of the balloonc. it is halfway between the balloon center and the inside surfaced. it is anywhere inside (the force is zero everywhere)

59. A MOSFET differs from JFET mainly because

a. of the power ratingb. the JFET has a pn junction c. MOSFETS do not have a physical channeld. the MOSFET has two gates

60. Consider Gauss’s law: ∮E∙dA= qε

, which of the following is true?

a. E must be the electric field due to the enclosed charge

b. If q = 0, then E = 0 everywhere on the Gaussian surface c. If the three particles inside have charges of +q, +q, and -2q, then the integral is zerod. on the surface E is everywhere parallel to dA

61. You wish to triple the rate of energy dissipation in a heating device. To do this you could triple

a. the potential difference keeping the resistance the sameb. the current keeping the resistance the samec. the resistance keeping the potential difference the samed. the resistance keeping the current the same

62. A uniform magnetic field is in the positive z direction. A positively charged particle is moving in the positive x direction through the field. The net force on the particle can be made zero by applying an electric field in what direction?

a. Positive y b. Negative y c. Positive x d. Negative x

63. For a certain p-channel JFET, VGS(off) = 8 V. The value of VGS for an approximately midpoint bias is

a. 2.34 V b. 0 V c. 4 V d. 1.25 V

64. When forward-biased, a diode

a. block current b. has a high resistanceb. conducts current d. drops a large voltage

65. An ion with a charge of +3.2x10-19 C is in a region where a uniform electric field of 5x104

V/m is perpendicular to a uniform magnetic field of 0.8T. If its acceleration is zero then its speed must be

a. 0 b. 1.6x104 m/s c. 4.0x104 m/s d. 6.3x104 m/s

66. When the rms output voltage of a bridge full wave rectifier is 20 V, the peak inverse voltage across the diodes is (neglecting the diode drop)

a. 28.3 V b. 20 V c. 40 V d. 56.6 V

67. The resistance of the primary coil of a well-designed, 1:10 step-down transformer is 1 Ω. With the secondary circuit open, the primary is connected to a 12 V ac generator. The primary current is

a. essentially zerob. about 12 Ac. about 120 Ad. depends on the actual number of turns in the primary coil

68. The purpose of a bleeder resistor is to

a. Provide bias for a transistor b. Serve as a voltage divider c. Protect people against the danger of electric shock d. Reduce the current in a power supply

69. A bar magnet is placed vertically with its S pole up and its N pole down. Its B field at its center is

a. zero b. downc. up due to the magnet’s weight d. horizontal

70. A bar magnet is broken in half. Each half is broken in half again, etc. The observation is that each piece has both a north and south pole. This is usually explained by

a. Ampere’s theory that all magnetic phenomena result from electric currentsb. our inability to divide the magnet into small enough pieces c. Coulomb’s law d. Lenz’ law

71. The ideal dc output voltage of a capacitor-input filter is equal to

a. the average value of the rectified voltageb. the rms value of the rectified voltagec. the peak value of the rectified voltage d. A or B

72. A certain power supply filter produces an output with a ripple of 100 mV peak-to-peak and a dc value of 20 V. The ripple factor is

a. 0.005 b. 0.05 c. 0.02 d. 0.00005

73. A capacitor in an LC oscillator has a maximum potential difference of 15 V and a maximum energy of 360 µJ. At a certain instant the energy in the capacitor is 40 µJ. At that instant what is the potential difference across the capacitor?

a. zero b. 5 V c. 10 V d. 15 V

74. When a voltmeter is placed across a forward-biased diode, it will read a voltage approximately equal to

a. the diode barrier potential b. the bias battery voltagec. the total circuit voltage d. 0 V

75. A voltage typical of a dry cell is

a. 12 V b. 6 V c. 1.5 V d. 117 V

76. In an oscillating LC circuit, the total stored energy is U and the maximum charge on the capacitor is Q. When the charge on the capacitor is Q/2, the energy stored in the inductor is

a. U/2 b. U/4c. 3U/2 d. 3U/4

77. The rapid exponential decay in just a few cycles of the charge on the plates of capacitor in an RLC circuit might be due to

a. a large inductance b. a large capacitancec. a small capacitance d. a large resistance

78. An inductor works by

a. Charging a piece of wire b. Storing energy as a magnetic field c. Choking off high-frequency ac d. Introducing resistance into a circuit

79. A battery is used to charge a series combination of two identical capacitors. If the potential difference across the battery terminals is V and total charge Q flows through the battery during the charging process then the charge on the positive plate of each capacitor and the potential difference across each capacitor are

a. Q/2 and V/2, respectively b. Q and V, respectively c. Q/2 and V, respectively d. Q and V/2, respectively

80. Load regulations is determined by

a. changes in zener current and load currentb. changes in load current and output voltagec. changes in load current and input voltaged. changes in load resistance and input voltage

81. The magnitude of the Bohr magneton in J/T is about

a. 10-15 b. 10-19

c. 10-23 d. 10-27

82. Two parallel-plate capacitors with different plate separation but the same capacitance are connected in series to a battery. Both capacitors are filled with air. The quantity that is NOT the same for both capacitors when they are fully charged is

a. potential difference b. stored energyc. electric field between the plates d. charge on the positive plate

83. Holes in an n-type semiconductor are

a. minority carriers that are thermally producedb. majority carriers that are thermally producedc. minority carriers that are produced by dopingd. majority carriers that are produced by doping

84. A dc electromagnet

a. Has constant polarity. b. Requires a core with high retentivity c. Will not attract or repel a permanent magnet d. Has polarity that periodically reverses

85. The molecular theory of magnetism can explain each of the following EXCEPT

a. an N pole attracts a S poleb. stroking an iron bar with a magnet will magnetize the barc. when a bar magnet is broken in two, each piece is a bar magnetd. heating tends to destroy magnetization

86. The gain of an amplifier without feedback is 100 dB. If a negative feedback of 3 dB is applied, the gain of an amplifier will become _________ .

a. 103 dB b. 101.5 dB c. 300 dB d. 97 dB

87. A trivalent impurity is added to silicon to create

a. germanium b. an n-type semiconductorc. a depletion region d. a p-type semiconductor

88. A chemical compound

a. Consists of two or more atoms b. Contains an unusual number of neutrons c. Is technically the same as ion d. Has a shortage of electrons89. Lenz’ law can explain

a. paramagnetism onlyb. diamagnetism onlyc. ferromagnetism onlyd. only two of the three types of magnetism

90. When negative feedback is applied to an amplifier, its gain _______ .

a. is increased b. is reducedc. remains the same d. approaches zero

91. Line regulations is determined by

a. zener current and load currentb. changes in load resistance and output voltagec. load currentd. changes in output voltage and input voltage

92. The value of negative feedback fraction is always _______ .

a. less than 1 b. more than 1c. equal to 1 d. equal to π/2

93. When the peak output voltage is 100 V, the PIV for each diode in a center-tapped full-wave rectifier is (neglecting the diode drop)

a. 100 V b. 141 V c. 200 V d. 50 V

94. A geomagnetic storm

a. Causes solar windb. Causes charged particles to bombard the earthc. Can disrupt the earth’s magnetic fieldd. Ruins microwave communications

95. If the output of an amplifier is 10 V and 100 V mV from the output is feedback to the input, then feedback fraction is ________ .

a. 10 b. 0.01 c. 0.1 d. 0.15

96. The core of a transformer is made in a laminated form to

a. facilitate easy assembly b. reduce i2R losses in the coilsc. increase the magnetic flux d. prevent eddy currents

97. Which of the following does not affect the inductance of a coil?

a. The diameter of the wire b. The number of turns c. The type of core material d. The length of the coil

98. For an ohmic resistor, resistance is the proportionality constant for

a. potential difference and electric fieldb. current and electric fieldc. current and lengthd. current and potential difference

99. A 60 V peak full-wave rectified voltage is applied to a capacitor-input filter. If f = 120 Hz. RL = 10 k Ω and C = 10 µF, the ripple voltage is

a. 0.6 V b. 5 V c. 6 mV d. 2.88 V

100. Two inductors, having values of 44 mH and 88 mH, are connected in series with a coefficient of coupling equal to 1.0 (maximum possible mutual inductance). If their fields reinforce, the net inductance is

a. 7.5 mH b. 132 mH c. 190 mH d. 260 mH

DE LA SALLE UNIVERSITY - DASMARINAS

Engineering DepartmentElectronics Engineering Program

ELECTRONICS

Name: _______________________________ Course/Year/Section ______________ Score

TEST I. Choose the letter that corresponds to the correct answer on the space provided on the answer sheet.

1. A software use in robotics wherein it is capable of moving any single degree of freedom to any intermediate point between the two extreme positions.

a. point-to-stop software b. point-to-point softwarec. continuous-path software d. discreet-path software

2. Two inductors, each of 100 µH, are in series. The coefficient of coupling is 0.40. The net inductance, if the coil fields reinforce each other, is

a. 50 µH b. 120 µHc. 200 µH d. 280 µH

3. A charged point particle is placed at the center of a spherical Gaussian surface. The electric flux ϕE is changed if

a. the sphere is replaced by a cube of the same volumeb. the sphere is replaced by a cube of one-tenth the volumec. the point charge is moved off centerd. the point charge is moved to just outside the sphere

4. The peak value of the input to a half-wave rectifier is 10 V. The approximate peak value of the output is

a. 10.7 V b. 9.3 Vc. 10 V d. 3.18 V

5. A watt hour meter measures

a. Voltage b. Current

General Direction:1. Use pencil number (2) only.2. Erasures in the final answers are considered incorrect.3. Use of cellular phone and programmable calculators are not allowed.4. Write all required answers and computations on the answer sheet provided.

c. Power d. Energy

6. A connection of branches forming a closed-path passing through any node only once is called a

a. junction b. meshc. loop d. circuit

7. Let Q denote charge, V denote potential difference, and U denote stored energy. Of these quantities, capacitors in parallel must have the same:

a. Q only b. V onlyc. U only d. Q and U only

8. How many lines are there in the data bus?

a. 10 b. 6c. 8 d. 12

9. If the resistance of a capacitor-filtered full full-wave rectifier is reduced, the ripple voltage

a. is not affected b. increasesc. decreases d. has a different frequency

10. In a highly inductive circuit, a small capacitance is added in series. The phase difference between the voltage and current will

a. increase b. decreasec. remain the same d. slightly change

11. If the feedback fraction in an amplifier is 0.01, then gain with negative feedback is approximately _____.

a. 10 b. 100c. 1000 d. 500

12. An RLC circuit has a capacitance of 12 µF, an inductance of 25 mH, and a resistance of 60Ω. The current oscillates with an angular frequency of

a. 1.2 x 103 rad/s b. 1.4 x 103 rad/sc. 1.8 x 103 rad/s d. 2.2 x 103 rad/s

13. Which of the following is a condition when a transistor is operating in the active region?

a. IB = βIE b. IC = βIB

c. IC = IB d. IC = IE

14. An advantage of an alkaline cell over a zinc-carbon cell is that:

a. The alkaline cell provide more voltageb. The alkaline cell can be rechargedc. An alkaline cell works at lower temperaturesd. The alkaline cell is far less bulky for the same amount of energy capacity

15. When a PLL is locked on the input frequency, the VCO frequency

a. Is less than fo b. Is greater than fo

c. Equals fin d. Equals fo

16. The process of adding an impurity to an intrinsic semiconductor is called

a. atomic modification b. dopingc. recombination d. ionization

17. Which of the following motors requires both AC and DC power supplies to run it?

a. Universal motor b. Induction motorc. Synchronous motor d. Wound rotor motor

18. The majority carriers in an n-type semiconductor are

a. holes b. conduction electronsc. valence electron d. protons

19. A device commonly used for remote switching of wire communications signal is

a. A solenoid b. An electromagnetc. A potentiometer d. A photovoltaic cell

20. A student kept her 60-watt, 120-volt study lamp turned on from 2:00 PM until 2:00 AM. How many coulombs of charge went through it?

a. 150 b. 3,600c. 7,200 d. 21,600

21. A hydrogen atom that has lost its electron is moving east in a region where the magnetic field is directed from south to north. It will be deflected

a. up b. downc. north d. south

22. NICAD memory

a. Occurs often when NICADs are misusedb. Indicates that the cell or battery is deadc. Does not occur very oftend. Can cause a NICAD to explode

23. An RL circuit has an impedance of Z = 6 + j8 ohms. What is the susceptance?

a. 6 b. 0.01c. 8 d. 0.08

24. What type of voltage is induced in a loop of wire rotating in a strong and steady magnetic field?

a. Pulsating dc b. rectified acc. dc d. ac

25. When a 60 Hz sinusoidal voltage is applied to the input of a half-wave rectifier, the output frequency is

a. 60 Hz b. 120 Hzc. 0 Hz d. 30 Hz

26. Every chemical element has its own unique type of particle, called its

a. Molecule b. Electronc. Proton d. Atom

27. What is the most common impurity found in the battery electrolyte?

a. HCl b. Leadc. Iron d. Water

28. A megaohmmeter is usually designed for measuring which of the following?

a. Very high resistance b. ground faults in power linesc. Very low resistance d. Overloads on dc motors

29. Which of the following is TRUE about FET?

a. It has a forward biased PN junctionb. It has a very high input resistancec. It has a very low input resistanced. It has a high connection emitter junction

30. Static electricity is most often produced by which of the following?

a. Pressure b. Magnesiumc. Heat d. Friction

31. Which of the following is TRUE about a shift register?

a. It stores both serial and parallel datab. Converts serial data to parallelc. Converts parallel data to seriald. All of these

32. What circuit element used to resonate with capacitor?

a. resistors b. Transistorsc. Inductors d. Diodes

33. The average value of a half-wave rectified voltage with a peak value of 200 V is

a. 127.3 V b. 141 Vc. 0 V d. 63.7 V

34. An advantage of magnetic disk over magnetic tape for data storage is that

a. Data is too closely packed on the tapeb. The disk is immune to the effects of magnetic fieldsc. Data storage and retrieval is faster on diskd. Disks store computer data in analog form

35. The positive lead of an ohmmeter is connected to the anode of a diode and the negative lead is connected to the cathode. The diode is

a. reverse-biased b. forward-biasedc. open d. faulty

36. Primary cells

a. Can be used over and overb. Have higher voltage than other types of cellsc. All have exactly 1.500 Vd. Cannot be recharged

37. In order to show that a resistor has a tolerance of ±10%

a. The third band must be silverb. No color in the fourth bandc. The fourth band is gold

d. The fourth band must be silver

38. A certain D-MOSFET is biased at VGS = 0 V. Its data sheet specifies IDSS = 20 mA and VGS(off)

= -5 V. The value of the drain current

a. is 0 A b. is 5 mAc. is 20 mA d. is 50 mA

39. Which of the following is similar to a de-multiplexer?

a. Decoder b. Data selectorc. Encoder d. Operator

40. An n-channel D-MOSFET with positive VGS is operating in

a. the depletion mode b. cutoffc. the enhancement mode d. saturation

41. Emitter follower is another name for what transistor configuration?

a. Common emitter b. Common basec. Common collector d. All of these

42. Why is the core of a transformer laminated?

a. To reduce the volume of core usedb. To reduce eddy lossc. To decrease the overall weight of the cored. To reduce the copper loss

43. A feature that distinguishes the J-K flip-flop from the S-R flip-flop is the

a. toggle condition b. preset inputc. type of clock d. clear input

44. At DC steady state, an inductor acts like which of the following?

a. an open circuit b. a capacitorc. a short circuit d. an insulator

45. A MOSFET is a special type of

a. JFET b. D-MOSFETc. E-MOSFET d. A and C

46. What will happen if the control system has an excessive noise on it?

a. Overall gain is reducedb. Bandwidth is reducedc. The system will oscillated. The amplifying stages will saturate

47. What is the angular velocity for a 25-cycle circuit?

a. 3.1416 radian per second b. 377 radian per secondc. 157 radian per second d. 314 radian per second

48. For a certain JFET, IGSS= 10 V. The input resistance is

a. 1 MΩ b. 1000 MΩc. 100 MΩ d. 1000 mΩ

49. Which of the following is TRUE about a signal flow graph?

a. It is a special type of graph for analysis of modern control system b. It is a semi-log graph c. It is a log-log graph d. It is a topological representation of asset of differential equation

50. What is the name of resistance wire wrapped around an insulating core?

a. Film-type b. Carbon compositionc. Fusible type d. Wire wound

51. The magnitude of the charge on an electron is approximately

a. 1023 C b. 10-23 Cc. 1019 C d. 10-19 C

52. A silicon diode is in series with 1.0 kΩ resistor and a 5 V battery. If the anode is connected to the positive battery terminal, the cathode voltage with respect to the negative battery terminal is

a. 0.7 V b. 5.7 Vc. 0.3 V d. 4.3 V

53. The total negative charge on the electrons in 1 mol of helium (atomic number 2, molar mass 4) is

a. 4.8 x 104 C b. 9.6 x 104 Cc. 1.9 x 105 C d. 3.8 x 105 C

54. A rheostat

a. Is used in high-voltage and/or high-power dc circuitsb. Is ideal for tuning a radio receiver

c. Is often used as a bleeder resistord. Is better than a potentiometer for low-power audio

55. A particle with a charge of 5 x 10-6 C and a mass of 20 g moves uniformly with a speed of 7 m/s in a circular orbit around a stationary particle with a charge of -5 x 10 -6 C. The radius of the orbit is:

a. 0 m b. 0.23 mc. 0.62 m d. 1.6 m

56. The purpose of a pentavalent impurity is to

a. increase the number of free electronsb. create minority carriersc. reduce the conductivity of silicond. increase the number of holes

57. A material with high permeability

a. increases magnetic field quantityb. is necessary if a coil is to produce a magnetic fieldc. always has high retentivityd. concentrates magnetic lines of flux

58. Charge is distributed uniformly on the surface of a spherical balloon (an insulator). A point particle with charge q is inside. The electrical force on the particle is greatest when

a. it is near the inside surface of the balloonb. it is at the center of the balloonc. it is halfway between the balloon center and the inside surfaced. it is anywhere inside (the force is zero everywhere)

59. A MOSFET differs from JFET mainly because

a. of the power ratingb. the JFET has a pn junction

c. MOSFETS do not have a physical channeld. the MOSFET has two gates

60. Consider Gauss’s law: ∮E∙dA= qε

, which of the following is true?

a. E must be the electric field due to the enclosed charge b. If q = 0, then E = 0 everywhere on the Gaussian surface

c. If the three particles inside have charges of +q, +q, and -2q, then the integral is zerod. on the surface E is everywhere parallel to dA

61. You wish to triple the rate of energy dissipation in a heating device. To do this you could triple

a. the potential difference keeping the resistance the sameb. the current keeping the resistance the samec. the resistance keeping the potential difference the samed. the resistance keeping the current the same

62. A uniform magnetic field is in the positive z direction. A positively charged particle is moving in the positive x direction through the field. The net force on the particle can be made zero by applying an electric field in what direction?

a. Positive y b. Negative y c. Positive x d. Negative x

63. For a certain p-channel JFET, VGS(off) = 8 V. The value of VGS for an approximately midpoint bias is

a. 2.34 V b. 0 V c. 4 V d. 1.25 V

64. When forward-biased, a diode

a. block current b. has a high resistanceb. conducts current d. drops a large voltage

65. An ion with a charge of +3.2x10-19 C is in a region where a uniform electric field of 5x104

V/m is perpendicular to a uniform magnetic field of 0.8T. If its acceleration is zero then its speed must be

a. 0 b. 1.6x104 m/s c. 4.0x104 m/s d. 6.3x104 m/s

66. When the rms output voltage of a bridge full wave rectifier is 20 V, the peak inverse voltage across the diodes is (neglecting the diode drop)

a. 28.3 V b. 20 V c. 40 V d. 56.6 V

67. The resistance of the primary coil of a well-designed, 1:10 step-down transformer is 1 Ω. With the secondary circuit open, the primary is connected to a 12 V ac generator. The primary current is

a. essentially zerob. about 12 Ac. about 120 Ad. depends on the actual number of turns in the primary coil

68. The purpose of a bleeder resistor is to

a. Provide bias for a transistor b. Serve as a voltage divider c. Protect people against the danger of electric shock d. Reduce the current in a power supply

69. A bar magnet is placed vertically with its S pole up and its N pole down. Its B field at its center is

a. zero b. downc. up due to the magnet’s weight d. horizontal

70. A bar magnet is broken in half. Each half is broken in half again, etc. The observation is that each piece has both a north and south pole. This is usually explained by

a. Ampere’s theory that all magnetic phenomena result from electric currentsb. our inability to divide the magnet into small enough pieces

c. Coulomb’s law d. Lenz’ law

71. The ideal dc output voltage of a capacitor-input filter is equal to

a. the average value of the rectified voltageb. the rms value of the rectified voltagec. the peak value of the rectified voltage

d. A or B

72. A certain power supply filter produces an output with a ripple of 100 mV peak-to-peak and a dc value of 20 V. The ripple factor is

a. 0.005 b. 0.05 c. 0.02 d. 0.00005

73. A capacitor in an LC oscillator has a maximum potential difference of 15 V and a maximum energy of 360 µJ. At a certain instant the energy in the capacitor is 40 µJ. At that instant what is the potential difference across the capacitor?

a. zero b. 5 V c. 10 V d. 15 V

74. When a voltmeter is placed across a forward-biased diode, it will read a voltage approximately equal to

a. the diode barrier potential b. the bias battery voltagec. the total circuit voltage d. 0 V

75. A voltage typical of a dry cell is

a. 12 V b. 6 V c. 1.5 V d. 117 V

76. In an oscillating LC circuit, the total stored energy is U and the maximum charge on the capacitor is Q. When the charge on the capacitor is Q/2, the energy stored in the inductor is

a. U/2 b. U/4c. 3U/2 d. 3U/4

77. The rapid exponential decay in just a few cycles of the charge on the plates of capacitor in an RLC circuit might be due to

a. a large inductance b. a large capacitancec. a small capacitance d. a large resistance

78. An inductor works by

a. Charging a piece of wire b. Storing energy as a magnetic field c. Choking off high-frequency ac d. Introducing resistance into a circuit

79. A battery is used to charge a series combination of two identical capacitors. If the potential difference across the battery terminals is V and total charge Q flows through the battery during the charging process then the charge on the positive plate of each capacitor and the potential difference across each capacitor are

a. Q/2 and V/2, respectively b. Q and V, respectively c. Q/2 and V, respectively d. Q and V/2, respectively

80. Load regulations is determined by

a. changes in zener current and load currentb. changes in load current and output voltagec. changes in load current and input voltaged. changes in load resistance and input voltage

81. The magnitude of the Bohr magneton in J/T is about

a. 10-15 b. 10-19

c. 10-23 d. 10-27

82. Two parallel-plate capacitors with different plate separation but the same capacitance are connected in series to a battery. Both capacitors are filled with air. The quantity that is NOT the same for both capacitors when they are fully charged is

a. potential difference b. stored energyc. electric field between the plates d. charge on the positive plate

83. Holes in an n-type semiconductor are

a. minority carriers that are thermally producedb. majority carriers that are thermally producedc. minority carriers that are produced by dopingd. majority carriers that are produced by doping

84. A dc electromagnet

a. Has constant polarity. b. Requires a core with high retentivity c. Will not attract or repel a permanent magnet d. Has polarity that periodically reverses

85. The molecular theory of magnetism can explain each of the following EXCEPT

a. an N pole attracts a S poleb. stroking an iron bar with a magnet will magnetize the barc. when a bar magnet is broken in two, each piece is a bar magnetd. heating tends to destroy magnetization

86. The gain of an amplifier without feedback is 100 dB. If a negative feedback of 3 dB is applied, the gain of an amplifier will become _________ .

a. 103 dB b. 101.5 dB c. 300 dB d. 97 dB

87. A trivalent impurity is added to silicon to create

a. germanium b. an n-type semiconductorc. a depletion region d. a p-type semiconductor

88. A chemical compound

a. Consists of two or more atoms

b. Contains an unusual number of neutrons c. Is technically the same as ion d. Has a shortage of electrons89. Lenz’ law can explain

a. paramagnetism onlyb. diamagnetism onlyc. ferromagnetism onlyd. only two of the three types of magnetism

90. When negative feedback is applied to an amplifier, its gain _______ .

a. is increased b. is reducedc. remains the same d. approaches zero

91. Line regulations is determined by

a. zener current and load currentb. changes in load resistance and output voltagec. load currentd. changes in output voltage and input voltage

92. The value of negative feedback fraction is always _______ .

a. less than 1 b. more than 1c. equal to 1 d. equal to π/2

93. When the peak output voltage is 100 V, the PIV for each diode in a center-tapped full-wave rectifier is (neglecting the diode drop)

a. 100 V b. 141 V c. 200 V d. 50 V

94. A geomagnetic storm

a. Causes solar windb. Causes charged particles to bombard the earthc. Can disrupt the earth’s magnetic fieldd. Ruins microwave communications

95. If the output of an amplifier is 10 V and 100 V mV from the output is feedback to the input, then feedback fraction is ________ .

a. 10 b. 0.01 c. 0.1 d. 0.15

96. The core of a transformer is made in a laminated form to

a. facilitate easy assembly b. reduce i2R losses in the coilsc. increase the magnetic flux d. prevent eddy currents

97. Which of the following does not affect the inductance of a coil?

a. The diameter of the wire b. The number of turns c. The type of core material d. The length of the coil

98. For an ohmic resistor, resistance is the proportionality constant for

a. potential difference and electric fieldb. current and electric fieldc. current and lengthd. current and potential difference

99. A 60 V peak full-wave rectified voltage is applied to a capacitor-input filter. If f = 120 Hz. RL = 10 k Ω and C = 10 µF, the ripple voltage is

a. 0.6 V b. 5 V c. 6 mV d. 2.88 V

100. Two inductors, having values of 44 mH and 88 mH, are connected in series with a coefficient of coupling equal to 1.0 (maximum possible mutual inductance). If their fields reinforce, the net inductance is

a. 7.5 mH b. 132 mH c. 190 mH d. 260 mH