ASVAB Practice

Electronics Information

160 Electronics Information practice questions, each with the correct answer and the method behind it.

Practice tests Practice test 1 Practice test 2 Practice test 3 Practice test 4 Practice test 5 Practice test 6 Practice test 7 Practice test 8
  1. Voltage in an electrical circuit is best described asthe pressure that pushes current through the circuit
  2. Electric current is measured inamperes
  3. Which of these materials is the best conductor of electricity?Copper
  4. The defining feature of alternating current is that itreverses direction at regular intervals
  5. Resistance in a circuitopposes the flow of current
  6. A static charge builds up on an object when the objectgains or loses electrons
  7. A 4 ohm heating element draws 3 amperes. What voltage is across it?12 volts
  8. What current flows when 12 volts is applied across 6 ohms?2 amperes
  9. A device draws 5 amperes at 120 volts. How much power does it use?600 watts
  10. How much current does a 60 watt bulb draw on a 120 volt supply?0.5 amperes
  11. What resistance allows 4 amperes to flow when 24 volts is applied?6 ohms
  12. A 1500 watt heater runs for 2 hours. How much energy does it use?3 kilowatt-hours
  13. How much power is dissipated in a 10 ohm resistor carrying 2 amperes?40 watts
  14. One milliampere is equal to0.001 ampere
  15. An ohmmeter is used to measureresistance
  16. To measure the voltage across a component, a voltmeter should be connectedin parallel with the component
  17. As the gauge number of a wire increases, the wirebecomes thinner and carries less current
  18. Three 6 ohm resistors are connected in series. What is the total resistance?18 ohms
  19. Two 10 ohm resistors are connected in parallel. What is the total resistance?5 ohms
  20. In a series circuit, the currentis the same at every point
  21. Each branch of a parallel circuit sees a voltage thatis the same as every other branch
  22. An open circuit is one in whichthe path is broken so no current flows
  23. A short circuit is hazardous becausecurrent bypasses the load and rises sharply
  24. The ground connection in an electrical system providesa safe path for fault current to flow away
  25. A capacitor stores energy in the form ofan electric field between its plates
  26. The coloured bands printed on a resistor indicate itsresistance value
  27. An inductor in a circuit opposesany change in the current through it
  28. A relay is best described asa switch operated by an electromagnet
  29. Connecting batteries in series producesa higher total voltage
  30. A resistor is banded brown, black, red. What is its resistance?1,000 ohms
  31. Which best describes how a diode behaves in a circuit?It conducts one way and blocks the other
  32. The process of converting alternating current into direct current is calledrectification
  33. In electronic circuits a transistor commonly serves asa switch or an amplifier
  34. An LED produces light whencurrent flows through it in the forward direction
  35. A fuse protects a circuit bymelting and breaking the circuit when current is too high
  36. The main advantage of a circuit breaker over a fuse is that a breakercan be reset instead of replaced
  37. A GFCI outlet protects a person bydetecting current leaking to ground and cutting power
  38. The frequency of an alternating current is measured inhertz
  39. A step-down transformerreduces voltage from primary to secondary
  40. A transformer has 100 turns on the primary and 50 on the secondary. With 240 volts applied to the primary, what is the secondary voltage?120 volts
  41. A semiconductor is a material thatconducts better than an insulator but worse than a metal
  42. Conventional current is described as flowingfrom the positive terminal to the negative
  43. The quantity of electric charge is measured incoulombs
  44. In a direct current circuit, the currentflows in one direction only
  45. Electrical wires are insulated chiefly tostop conductors from touching each other or a person
  46. Within a metal conductor, the electrons themselves driftfrom the negative terminal toward the positive
  47. If the resistance of a circuit doubles while the voltage stays the same, the currentfalls to half its former value
  48. A 20 ohm load is connected to a 240 volt supply. What current flows?12 amperes
  49. A device draws 2 amperes at 9 volts. What is its power consumption?18 watts
  50. A circuit operating at 6 volts carries 2 amperes. What is its resistance?3 ohms
  51. A 100 watt bulb is left on for 10 hours. How much energy does it consume?1 kilowatt-hour
  52. What voltage appears across a 5 ohm resistor carrying 3 amperes?15 volts
  53. A component dissipating 20 watts operates at 10 volts. What current does it draw?2 amperes
  54. One kilovolt is equal to1000 volts
  55. To read the current in a circuit, an ammeter must be connectedin series, so all the current passes through it
  56. One microfarad is equal to0.000001 farad
  57. Inductance is measured inhenries
  58. A 4 ohm and an 8 ohm resistor are connected in series. What is the total resistance?12 ohms
  59. Three 30 ohm resistors are connected in parallel. What is the total resistance?10 ohms
  60. Adding more branches to a parallel circuit causes the total resistance todecrease
  61. In a schematic diagram, a symbol made of alternating long and short parallel lines representsa battery
  62. A series-parallel circuit is one thatcontains both series and parallel connections
  63. Household outlets are wired in parallel so thateach device gets full voltage and works independently
  64. If one branch of a parallel circuit develops an open, the remaining branchescontinue to operate normally
  65. A potentiometer is a type ofvariable resistor
  66. Capacitance is measured infarads
  67. A transformer will operate only onalternating current
  68. A heat sink is fitted to an electronic component in order tocarry heat away from the component
  69. A single-pole, single-throw switchopens or closes one circuit
  70. A secondary cell differs from a primary cell in that a secondary cellcan have its chemical reaction reversed by charging
  71. An integrated circuit ismany components built onto a single chip
  72. How many terminals does a standard transistor have?Three
  73. How many diodes are used in a full-wave bridge rectifier?Four
  74. Doping a semiconductor meansadding small amounts of another element to change its conductivity
  75. Before working on a circuit you believe is switched off, you shouldconfirm it is dead with a meter or tester
  76. When a fuse blows, it should be replaced with one ofthe same current rating
  77. The severity of an electric shock depends most directly onthe amount of current passing through the body
  78. The period of an alternating waveform isthe time taken for one complete cycle
  79. The inductive reactance of a coil increases whenthe frequency of the supply rises
  80. Impedance in an AC circuit isthe total opposition from resistance and reactance together
  81. Power in a DC circuit is best defined asthe rate at which electrical energy is converted to other forms
  82. A material through which electrons cannot easily move is calledan insulator
  83. Silver is prized in specialized wiring mainly because itconducts electricity slightly better than copper
  84. In an alternating current circuit, a single cycle is completed when the currentrises, falls, reverses, and returns to its starting value
  85. Compared with direct current, alternating current is favored for long-distance power transmission chiefly because itcan be stepped up and down efficiently with transformers
  86. A battery supplies direct current because the chemical reaction inside itpushes charge from one terminal to the other in a fixed direction
  87. Two charged objects with charges of the same sign, when brought near each other, willrepel one another
  88. Lightning is an example ofa large static discharge between a charged cloud and the ground
  89. Rubbing a plastic comb with wool typically leaves the combnegatively charged, because it picks up extra electrons
  90. A wire that offers exactly zero resistance to current flow is calleda superconductor
  91. Doubling the cross-sectional area of a copper conductor, with its length unchanged, causes its resistance todecrease to about half its former value
  92. The basic unit of electric current, the ampere, describeshow much charge passes a given point each second
  93. If a circuit has voltage applied but its resistance is essentially infinite, the current in that circuit isessentially zero
  94. An electric shock delivered to a person is caused directly bycurrent passing through body tissue
  95. A 15 ohm heater draws 2 amperes. What voltage is across it?30 volts
  96. What current flows when 18 volts is applied across 3 ohms?6 amperes
  97. A circuit carries 5 amperes when 25 volts is applied. What is its resistance?5 ohms
  98. A 9 volt battery drives 0.5 ampere through a resistor. What is the resistor's value?18 ohms
  99. If the voltage applied to a fixed resistor is tripled, the current through it willbecome three times as large
  100. A device consumes 250 watts while drawing 2 amperes. What voltage is it operating at?125 volts
  101. A motor operating at 240 volts draws 3 amperes. How much power does it use?720 watts
  102. A 1200 watt appliance is plugged into a 120 volt outlet. How much current does it draw?10 amperes
  103. A soldering iron rated at 480 watts on a 240 volt supply draws how much current?2 amperes
  104. A 2000 watt space heater runs for 3 hours. How much energy does it consume?6 kilowatt-hours
  105. A 250 watt television runs for 4 hours each day. How much energy does it use in that day?1 kilowatt-hour
  106. An appliance uses 5 kilowatt-hours of energy while running for 5 hours. What is its power rating?1000 watts
  107. How much power is dissipated in a 6 ohm resistor carrying 3 amperes?54 watts
  108. A resistor rated at 2 watts safely carries 0.5 ampere. What is the highest resistance it could have at that current without exceeding its rating?8 ohms
  109. One kilohertz is equal to1000 hertz
  110. One megohm is equal to1,000,000 ohms
  111. A voltmeter placed in series with a component, rather than in parallel, would most likelyblock nearly all current because of its very high internal resistance
  112. Before using an ohmmeter to test a resistor mounted in a circuit, you should firstremove power from the circuit
  113. Compared with 12 gauge wire, 22 gauge wire isthinner and has a lower safe current rating
  114. A multimeter set to measure resistance shows a reading of infinity across a suspect fuse. This indicates the fuse isopen, or blown
  115. Four 5 ohm resistors are connected in series. What is the total resistance?20 ohms
  116. A 3 ohm and a 7 ohm resistor are wired in series across a 20 volt supply. What is the total current in the circuit?2 amperes
  117. Two 12 ohm resistors are connected in parallel. What is the total resistance?6 ohms
  118. A 6 ohm and a 3 ohm resistor are connected in parallel. What is the total resistance?2 ohms
  119. In a series-parallel network, the first step in finding the total resistance is usually tocombine the parallel branches into a single equivalent resistance
  120. In a series-parallel circuit, a component wired in series with a parallel group willcarry the full current supplied to that group
  121. A dead short develops directly across the terminals of a battery. The current drawn from the battery willrise sharply, limited mainly by the battery's own internal resistance
  122. A broken filament inside a light bulb is an example ofan open circuit
  123. In a schematic diagram, a zigzag line most commonly representsa resistor
  124. In a schematic diagram, two parallel lines of equal length, one straight and one curved, are used to representa capacitor
  125. A properly grounded metal appliance case protects the user chiefly bygiving fault current a low-resistance path away from the user's body
  126. Connecting the metal frame of test equipment to a common ground point is done mainly tohold all connected equipment at the same reference voltage
  127. If a resistor in a purely series circuit fails as an open, the rest of the circuit willstop carrying any current at all
  128. Three resistors of 2, 3, and 6 ohms are connected in parallel. What is the total resistance?1 ohm
  129. A resistor is banded red, red, orange. What is its resistance?22,000 ohms
  130. A resistor is banded yellow, violet, brown. What is its resistance?470 ohms
  131. Connecting two capacitors of equal value in parallel produces a total capacitance that isdouble the value of one capacitor alone
  132. A capacitor blocks the flow ofsteady direct current, once it is fully charged
  133. An inductor is most simply constructed asa coil of insulated wire, often wound around a core
  134. A single-pole, double-throw switch is best suited to a circuit that mustroute power to either of two different paths from one source
  135. A relay is useful in a circuit mainly because it letsa low-power signal control a much higher-power load safely
  136. Connecting several identical cells in parallel, rather than in series, mainly increases the battery'savailable current and running time at the original voltage
  137. A lead-acid battery, like the type used to start a car, is an example of asecondary, rechargeable cell
  138. The tolerance band on a resistor's color code indicateshow far the actual resistance may vary from its marked value
  139. Wiring several capacitors in series, rather than in parallel, produces a total capacitance that isless than the smallest individual capacitor
  140. An inductor's ability to store energy comes from itsmagnetic field, built up as current flows through its coil
  141. A zener diode is specifically designed tomaintain a steady voltage when operated in reverse breakdown
  142. A half-wave rectifier built from a single diodepasses only one half of each AC cycle to the load
  143. In an NPN bipolar transistor, applying a small forward current to the base allowsa much larger current to flow between the collector and emitter
  144. An integrated circuit is typically manufactured on a thin wafer ofsilicon
  145. Compared with an incandescent bulb of similar brightness, an LED typicallyuses less power and lasts far longer
  146. A photodiode is a semiconductor device thatproduces a current in response to light striking it
  147. An LED must always be installed with attention to its polarity because itconducts, and lights, in only one direction
  148. A microcontroller chip found inside many modern appliances is an example ofan integrated circuit containing thousands or millions of components
  149. A fuse rated for 15 amperes is intended toopen the circuit once current exceeds about 15 amperes
  150. A circuit breaker that trips repeatedly under normal household load most likely indicatesa fault or overload somewhere on that circuit
  151. A ground fault circuit interrupter reacts toa difference between the current leaving and returning on its monitored wires
  152. When working around energized electrical equipment, standing on a dry rubber mat mainly helps byadding a high-resistance barrier between the worker and the ground
  153. Wet skin is more dangerous around electricity than dry skin chiefly because moisturelowers the skin's resistance, allowing more current to flow through the body
  154. The proper first action if you find a coworker still in contact with an energized conductor is tocut power to the circuit or use a non-conductive object to separate them from it
  155. A waveform completing 50 cycles every second has a frequency of50 hertz
  156. Two AC waveforms of the same frequency that reach their peaks at different instants are said to beout of phase with one another
  157. A step-up transformer with more turns on its secondary than its primary willraise the voltage delivered to the secondary circuit
  158. A transformer has 60 turns on its primary and 240 turns on its secondary. With 120 volts applied to the primary, what is the secondary voltage?480 volts
  159. A transformer has 400 turns on its primary and 100 turns on its secondary. With 100 volts applied to the primary, what is the secondary voltage?25 volts
  160. The capacitive reactance of a capacitor decreases as thefrequency of the applied AC signal increases

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