ELECTRONICS1. A diac has _____ semiconductor layers. a. 1 c. 3 b. 2 d. 4 2. a. Which of the following is false? A carbon-zinc cell has unlimited shelf life. b. c. d. 3. A storage cell has a reversible chemical reaction. The speed of a dc shunt motor can be slowed down under one of the conditions below. a. decreased field voltage b. c. increased field voltage 4. 5. d. increased armature voltage increased armature resistance At series resonance, the circuit impedance is equal to _____. a. R c. XC b. C d. XL The source terminal of a FET corresponds to the _____ of a vacuum tube. a. grid c. b. 6. 7. A lead-acid cell can be recharged. A primary cell has an irreversible chemical reaction. cathode base d. plate A ROM has 6 inputs and 8 outputs. How many bits does the ROM store? a. 512 c. 4096 b. 2048 d. 6400 When current in a conductor increases, Lenz law says that the self-induced voltage will _____. a. b. c. d. 8. aid the applied voltage tend to increase the amount of current produce current opposite to the increasing current In transistor amplifiers, we use _____ transformer for impedance matching. a. b. step up c. step down 9. a. aid the increasing current d. Which of the following is an n-type semiconductor? doped by acceptor atom b. same turn ratio none of the above c. majority carriers are holes crystal with pentavalent impurities d. minority carriers are free electrons 10. What is the output power of an amplifier having an output of 12 dBm? a. 0.38 mW b. c. 24 mW 15.85 mW d. 251 W 11. A relay is superior to a mechanical switch because it _____. a. is relatively inexpensive b. c. combines control with power amplification is operated mechanically d. does not require moving contacts o 12. Assuming a barrier potential of 0.7 V at an ambient temperature of 25 C, what is the barrier potential of a silicon diode when the junction o temperature is 75 C? a. 0.5 c. 0.7 b. 0.6 d. 0.8 13. Two diodes are in series. The first diode has a voltage of 0.75 V and the second has a voltage of 0.8 V. If the current through the first diode is 500 mA, what is the current through the second diode? a. 242 mA c. 500 mA b. 258 mA d. 533 mA 14. What is the application of laser diode? a. b. line-spike protectors high frequency rectifiers c. d. high-frequency oscillators CD players, broadband communications 8 c. a. Find the frequency in kilocycles per second in the armature of a 10-pole 1. cathode d.7 d.132 mA c. depends on the factor 2π c. increases with lower frequencies b. Which of the following statements is true? a. 200 V b. saturation avalanche d.25 W c. 1. a. 0. Alnico is commonly used for electromagnets. 0. Inductive reactance applies only to sine waves because it _____.15 V c. If XL = 5 kΩ and XC = 25 Ω. anode c. 0. varactor back diode c.5 mA 28. capacitive none of the above 25. 10 1000 d. 26.6 % d. d. 100 W . 6 KV o 20. jointed-arm and electric b. 75 95. Find the power across the resistor of 5 Ω delivered from a battery of an internal resistance of 3 Ω and a constant emf of 4 volts. cut-off b. 18. a. forward-biased 16. Iron is generally used for permanent magnets. a. a. A half-wave signal with a peak of 30 V is the input of a choke-input filter. a. When a transistor is conducting as much as it possibly can.1 c. It is used in TV and receiver tuners. b. a. c. a. 21. inductive d. 26. c. 20 % b. compute the efficiency of the rectifier in percentage. a series LC circuit behaves as a _____ load.0625 μs a. articulated arm and cylindrical c. Silicon diodes are used in a two-diode full-wave rectifier circuit to supply a load of 12 Vdc.2 b.15 mA. it is said to be in _____. b.15.5 μs d. what is the collector current? a. spherical and hydraulic 19. 80 % 22. 1024 not determined by sets of input 24. 3. increases with lower inductance 23. d. If the base current is 0. b. c. What is the control element in an SCR? a. what is the approximate peak-to-peak ripple across the capacitor? a. Ferrites have lower permeability than air or vacuum Paper cannot affect magnetic flux because it is not a magnetic material. A transistor has a current gain of 175. A memory circuit that has 9 address inputs has how many storage locations? a. Assuming ideal diodes and the load resistance is 12 Ω.062 A b. For frequencies below resonant frequency. 81. 17. 17. 0. One dB corresponds to _____ change in voltage or current level. a. 256 c. 5. 40 % 63. spherical and pneumatic d. The _____ are two of the most common mechanical configurations of industrial robots. 100 b. Calculate the time delay for a phase angle of 55 at the frequency of 2 MHz.0764 μs b. 0.200 rpm generator. 0.152 μs c.25 mA d. 5 mV d. 512 d. decreases with higher frequencies d. 0. base b. gate 29. b. resistive c. optocoupler step-recovery diode 27. d. If an ohmmeter check on a 50 μH choke reads 3 Ω. a. c. common gate c. partially open 37. decrease the forward current prevent excessive temperature rise d. a. The purpose of capacitors in a transistor amplifier is to _____. How much is the self-induced voltage across a 200-mH inductance produced by a current change of 0 to 10 mA in 2μs. A heat sink is generally used with a transistor to _____. Which of the following circuits generally has the greatest gain? a. current and stator impedance rotor emf. 300 dB 31. c. decreased remains the same d. increase gain reduce distortion c. 50 Ω b. a. If a negative feedback of 3 dB is applied.b. none of the above 33. c. b. b. increased b. 101. d. become zero 42. open c. power feedback c.5 dB d. 103 dB b. Parallel to serial data conversion can be performed by a _____. the gain of the amplifier will become _____. holes b. shift counter binary counter d. 10. a. voltage. The torque developed by a three-phase induction motor depends on the following three factors: a. a. BCD counter c. rotor current and stator impedance c. the total impedance is equal to _____. a.000 V 100 V d. 97 dB c. 120 W 30. silver oxide b. compensate for excessive doping 32. b. speed. 1. shift register 39. voltage feedback d. common source b. a. a. mercury oxide 35. d. 10 V c. a. common drain it depends on bias. provide biasing couple or bypass ac component . frequency and number of poles number of poles. rotor speed and frequency 40. lead-acid carbon-zinc d. Addition of trivalent impurity to a pure semi-conductor creates many _____. current feedback b. valence electrons 34. Which of the following cells has a reversible chemical reaction? a. increase forward current b. b. In a sine wave ac circuit with R = 40 Ω in series with XL = 30 Ω.000 V 38. 60 W d. 70 Ω 36. defective normal d. to have a negative coefficient keep the temperature within limits 43. b. The basic purpose of applying negative feedback to an amplifier is to _____. the coil is probably _____. 30 Ω c. b. d. The gain of an amplifier without feedback is 100 dB. What happened to the output of an SCR if the firing angle is increased? a. 40 Ω d. a. not on which electrode is grounded 41. c. free electrons bound electrons d. protect the transistor cool the transistor c. Emitter follower is a _____ circuit. to shift the input offset current to zero to set and/or adjust the input offset voltage to zero to set and/or to adjust the output voltage to zero when the input signal is zero d.1 c.288 J b.548 J 54. Plate resistance = Amplification x Transconductance 49. a. 51. A vacuum diode can act as _____. a rectifier an amplifier c.2 A flows in a coil with inductance of 0. detector stage RF stage d. c. Amplification factor x Plate resistance x Transconductance = 1 c. 1. glass cockpit b. The reverse resistance and forward resistance of crystal diode have a ratio of about _____. 1000:1 48. power stage 47. The term semiconductor arises from _____. mixer stage b. an oscillator a multivibrator 57. The output stage in an amplifier is also called _____. 0. 1. machining d. all of the above 50. 40 % d. How much energy is stored in the magnetic field? a. b.8 H. c. The relation between the three dynamic parameters of a vacuum tube triode is given by the formula _____. 2 c. 8 45. a. A two-pole three-phase motor has _____ field poles. b. 1. a. SCARA robots has four axis of motion and is used in ______. Transconductance = Plate resistance x Amplification factor d. The maximum plate efficiency for class B operation is _____. 6 b. a. a. b. A current of 2. 25 μH c. insulated gate 53. 200 μH b. What is the purpose of a level shifter in op-amps? a. c. virtual cockpit 46. A secondary battery Zinc-nickel oxide has a voltage of _____. Two series coils.5 % 52. 0. many gate shorted gate d. 1.936 J c. welding c. open gate c. a. 300 μH . b.88 J d. b. real cockpit d. 100 μH d.8 56. 35 % c. a. a. 250 μH each have a total inductance of 550 μH connected series-aiding and 450 μH series-opposing. 2. A new concept in commercial aircraft where computers monitor aircraft systems reporting to their status only if requested by pilot or if something is wrong and displayed on the screen when necessary. 1:1 c. a.44. d. 100:1 2:1 d. 1.6 d. 4 d. cockpit c. a. assembling handling heavy loads 55. A MOSFET is sometimes called _____ FET. 50 % 78.9 b. a. Amplification factor = Plate resistance ÷ Transconductance b. resistor-like properties of metal oxide insulating properties of silicon and GaAs variable conductive properties of metal oxides the fact that there’s nothing better to call silicon d. How much is the mutual inductance between the coil? a. b. b. 5 % ripple filtered voltage having a load of 120 mA. d. emitter is heavily doped c. Actuators used in industrial robots. 1. electric motors all of the above 69. low internal resistance b. modulating 63. a.58. advertising 68. A transistor has high output impedance because _____. c. ROM b. What is the circuit impedance at resonance? a. high internal resistance 65. When an alternating voltage reverses in polarity. A constant-voltage generator has _____. The main element of a microprogrammed controller is _____. collector has reverse bias collector is wider than emitter or base 59. c.6 ms b.2. A parallel LC circuit has a capacitor of 100 pF in one branch and an inductance of 100 μH plus a resistance of 10 Ω in the ot her branch. b. has a steady dc value o reverses in direction alternates 1. binary counter address register 61. a. 62. anode is negative with respect to cathode applied potential between anode and cathode are equal 67. the current it produces _____. A 0. b. 223. reading b. Find the mutual inductance of two 200 mH coils that has a coefficient of coupling k equal to 0. 1. 80 mH b. The Q of a tuned circuit refers to the property of _____.7 microfarad d. series switching d.7 microfarad c. c.7 ms 60. 1. 311. 40 mH c. shunt 100 kΩ c. a. 25 kΩ b. minimum current capacity d. a. PLA d. sensitivity none of the above 70. fidelity selectivity c. 1. a. How much time is required for Vc to discharge down to 132 V? a. c. How can electrical current be induced with a coil and a magnet? a. b. fluid motors c.4 times the frequency of the applied voltage 66. 3207 microfarad 64. a. aesthetics industrial d.4 ms c. a. 60 mH d. 100 mH 71. a.05 µF capacitor is charged to 264 V. cathode is positive with respect to anode cathode is negative with respect to anode c. b. 320. a. d. has a phase angle of 180 c. emitter has forward bias d. Floodlighting is not used for _____ applications. a. Which regulator is the most inefficient? b. moving either the magnet or the coil placing the coil parallel to the magnet field holding the coil and the magnet perfectly stationary . Diodes are said to be forward bias when the _____. b. 50 kΩ a.61 kΩ d. Find the filter capacitor that will provide 2. 3117 microfarad b. It charges through a 50 kΩ resistor. fluid cylinders d.5 ms d. d. minimum efficiency c. b. full-wave rectified voltage of 36 Vdc and 60 Hz supply. resistance 74. rejection mode d. b. cobalt d. V(t) = 5. 48. a.8 cos (ωt + 39) volts c. b. b. generally increase with direct current in a coil cannot be produced in an iron core because it is a conductor are caused by high-frequency alternating current in a coil with an iron core are especially important with permanent magnets that have a steady magnetic field 84. Which BCD code is used for data communications? a. when both inputs are tied together or when the input signal is common to both inputs. Determine the percentage error of reading of an ammeter due to ammeter insertion. a. the _____.76 c. 4. d. bulk resistance 77. b. a. 8421 BCD ASCII d.6 cos (ωt + 75) volts 82. proportional plus derivative proportional plus integral plus derivative 73. 12 hours d. current through the inductance lags its induced voltage by 90 o o d. V(t) = 25 cos (ωt + 75) volts d.9 cos (ωt + 71) volts b. Determine how long a battery will last whose rating is 100 Ah.4 k Ω. nickel c. iron aluminum 76. differential mode double-ended mode 81. pure binary 79. 26. 95 b. b. An amplifier with an input resistance of 600 ohms has an input current of 500 microamperes. 43. placing the coil at right angles with the magnetic field 72. intrinsic resistance dynamic resistance d. b. a. Proportional mode of control wherein the controller is not only considering the magnitude of the error signal but as well as its rate of change. c. phase angle of the circuit is always 45 o o b. a.2 dB d. a. A triode is considered to be a _____ amplifier. Given two voltages: S(t) = 10 cos (ωt + 30) volts and Q(t) = 15 cos (ωt + 45) volts. proportional c. d.8 dB 78. 5 96 d.2 dB b. Which of the following is not a ferromagnetic material? a. The operating mode of an op-amp. V(t) = 24. current through the inductance and voltage across it are 180 out of phase 83. Calculate the dB gain of the amplifier. 6. It delivers 100 mA to a 1000 Ω load. 24 volts and will run 300 W electronic equipment and a 50 W light. a. Ammeter parameters include 70 Ω internal resistance and a load resistor of 1.05 hours 75. c. Find V(t) = S(t) + Q(t). voltage power d. -48. extrinsic resistance b. proportional plus integral d. The resistance of a semiconductor is known as _____. -43. voltage across the inductance must be 90 out of phase with the applied voltage c. current b. c. a. common mode c.d. Hysteresis losses ______.65 hours b.85 hours c. Gray c. V(t) = 13. a. 80. In a sine-wave ac circuit with inductive reactance. c. a. causes an increase in the current in a wire concentrates magnetic flux lines within itself increases the number of ampere turns in wire increases the total magnetomotive force around a current-carrying wire . a. A ferromagnetic material _____. 50.8 dB c. 5 Ω b. a. The entire width of 10 cm then represents the time of ____. The term _____ reflects the fact that holes and electrons participate in the injection process into the oppositely polarized material. has a back emf opposing a steady direct current c. infinite resistance and normal inductance d. increases the amplitude of direct current increases the amplitude of alternating current 95. proton current c. one-quarter d. The first of a long lineage of microcomputer based group communications software. c. 3 x 10 Aּt/Wb b. 1. 15. The number of axis a robot is free to move is called _____. CBBS d. 1 msec 5 msec d. more than 1 M Ω d. a. varying magnetic field d. high peak value c. 5 x 10 Aּt/Wb 2 x 10 Aּt/Wb a. a. the inductance is _____. reduces the amplitude of alternating current b.85. the same c. a. 104 Ω 86. 0. NOVELL b. A magnetic material has a total flux of 60 μWb with an mmf of 180 Aּt. b. 0.0167 A c. zero resistance and inductance zero resistance and high inductance c. the horizontal time base is set for 5 ms/cm. A transformer with a 1:6 turns ratio has 720 V across 7200 Ω in the secondary. 0. Alternating current can induce voltage because alternating current has a _____.05 A d. The dc resistance of a coil made with 100 ft of No. b.1 A b. d. freedom axis b. movement degrees 89.5 msec c. constant magnetic field stronger magnetic field than direct current 97. a. polarization current 88. ionization current b. 0. 50 msec 91. b. With double the number of turns but the same length and area. A laminated iron core has reduced eddy-current losses because _____. 30 gage copper wire is approximately _____. a. electron current d. 4 x 10 Aּt/Wb 6 d. less than 1 Ω c. a. the magnetic flux is concentrated in the air gap of the core b.59 Hz c. b. pentode 90. double quadruple 96. E-mail c. c. 6 c. 1592 Hz 94. unipolar c. Calculate the reluctance in ampere-turns per weber. mechanical axis degrees of freedom d. a. For an oscilloscope with triggered sweep. Inductive reactance is measured in ohms because it _____. 0. d. The current flowing between electrodes inside a lead-acid battery is _____.9 Hz d. a. tetrode b. a. An open coil has _____. Find the secondary current. At what frequency will a 100 μF capacitor have Xc equal to 100 Ω? a. 6 6 92. 159 Hz b. a. the laminations are insulated the laminations are stacked vertically more wire can be used with less dc resistance in the coil 93. a. EMISARI . 10.6 A 87. bipolar d. infinite resistance and zero inductance 98. Which of the following are the advantages of hydraulic actuators? a. 108 µF . 105 µF c.99. All of the above 100. Intrinsically safe in flammable environment such as painting. b. 106 µF d. What value of C resonates with a 239 μH at 1. d. c. Accurate positioning and good velocity control. Great holding strength when stopped.000 Hz? a. 107 µF b.