MCQOPTIONS
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MCQOPTIONS
This section includes 1728 Mcqs, each offering curated multiple-choice questions to sharpen your Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 201. |
With 100 Vac applied to the primary of a transformer so that it draws 500 mA, what will be the 300 Vac secondary current? |
| A. | 1500 mA |
| B. | 200 mA |
| C. | 167 mA |
| D. | 150 mA |
| Answer» D. 150 mA | |
| 202. |
Which coil would be used as a step-up transformer primary if coil number 1 has 100 more turns than coil number 2? |
| A. | The coil windings must be the same. |
| B. | coil 1 |
| C. | The coil ratio is too small. |
| D. | coil 2 |
| Answer» E. | |
| 203. |
When the transformer secondary is not loaded: |
| A. | secondary voltage increases |
| B. | no secondary current flows |
| C. | no secondary voltage is present |
| D. | secondary current increases |
| Answer» C. no secondary voltage is present | |
| 204. |
When current in an inductor starts to change, it cannot react instantly due to: |
| A. | fixed coil resistance |
| B. | eddy current generation |
| C. | applied emf of the circuit |
| D. | the counter emf of the coil |
| Answer» E. | |
| 205. |
What is the approximate time for a complete decay of 400 mA of inductor current, when R = 10 ohms and L = 20 H? |
| A. | 10 seconds |
| B. | 8 seconds |
| C. | 4 seconds |
| D. | 2 seconds |
| Answer» B. 8 seconds | |
| 206. |
A utility pole transformer used to supply a residential customer with two phases uses: |
| A. | two phases on the primary |
| B. | a center tap on the secondary |
| C. | a separate ground for each phase |
| D. | a small coefficient of coupling |
| Answer» C. a separate ground for each phase | |
| 207. |
When a coil collapses the induced circuit current will: |
| A. | be in the same direction |
| B. | go to zero |
| C. | aid counter emf buildup |
| D. | be in the opposite direction |
| Answer» B. go to zero | |
| 208. |
When a rate of one ampere per second causes an induced voltage of one volt, the unit of measure is |
| A. | a lenz |
| B. | an ohm |
| C. | a farad |
| D. | a henry |
| Answer» E. | |
| 209. |
When a magnet enters a coil and a voltage is induced, the process is known as: |
| A. | an alternation |
| B. | self-inductance |
| C. | counter emf |
| D. | flux linkage |
| Answer» E. | |
| 210. |
What term is used to describe the action of magnetic flux from one circuit that cuts across the conductors of another circuit? |
| A. | self-inductance |
| B. | rectification |
| C. | mutual inductance |
| D. | magnetism |
| Answer» D. magnetism | |
| 211. |
Reactance in an inductive circuit will: |
| A. | increase with frequency |
| B. | decrease with frequency |
| C. | be independent from frequency |
| D. | depend on the value of X |
| E. | <sub>C</sub> |
| Answer» B. decrease with frequency | |
| 212. |
A turns ratio of 5 for a transformer implies: |
| A. | more primary turns than secondary turns |
| B. | more secondary current than primary current |
| C. | larger source impedance than load impedance |
| D. | more secondary turns than primary turns |
| Answer» E. | |
| 213. |
The time difference, or lag, between flux density and magnetizing force is known as: |
| A. | eddy current |
| B. | magnetic saturation |
| C. | hysteresis |
| D. | coercivity |
| Answer» D. coercivity | |
| 214. |
A magnetic circuit breaker will open to protect equipment only when: |
| A. | voltage is exceeded |
| B. | an open is in the equipment |
| C. | the equipment is operating properly |
| D. | current is exceeded |
| Answer» E. | |
| 215. |
Electromagnetic induction is the generation of: |
| A. | electricity from magnetism |
| B. | electricity from electricity |
| C. | magnetism from electricity |
| D. | magnetism from magnetism |
| Answer» B. electricity from electricity | |
| 216. |
Inductance is: |
| A. | directly proportional to the length of the coil |
| B. | directly proportional to the number of turns on the coil |
| C. | inversely proportional to the cross-sectional area of the coil |
| D. | inversely proportional to the permeability |
| Answer» C. inversely proportional to the cross-sectional area of the coil | |
| 217. |
Current will cause a magnetic field in a conductor as follows: |
| A. | An ac current causes a fixed polarity magnetic field. |
| B. | A dc current causes a fixed polarity magnetic field. |
| C. | A dc current causes an alternating magnetic field. |
| D. | An ac current causes a fixed polarity magnetic field and a dc current causes an alternating magnetic field. |
| Answer» C. A dc current causes an alternating magnetic field. | |
| 218. |
Electromagnetism is the: |
| A. | magnetic field caused by a permanent magnet |
| B. | action between a permanent and an artificial magnet |
| C. | magnetic field action with a current-carrying wire |
| D. | current in the coil |
| Answer» D. current in the coil | |
| 219. |
A magnetic field has: |
| A. | polar fields |
| B. | lines of force |
| C. | magnetomotive force |
| D. | lines of reluctance |
| Answer» C. magnetomotive force | |
| 220. |
Which two values are plotted on a B-H curve graph? |
| A. | reluctance and flux density |
| B. | permeability and reluctance |
| C. | magnetizing force and permeability |
| D. | flux density and magnetizing force |
| Answer» E. | |
| 221. |
What is the number of turns required in the secondary winding for a transformer when 120 volts is applied to a 2400-turn primary to produce 7.5 Vac at the secondary? |
| A. | 75 turns |
| B. | 150 turns |
| C. | 900 turns |
| D. | 1920 turns |
| Answer» C. 900 turns | |
| 222. |
The four factors determining inductance are the number of turns, coil length, coil area, and: |
| A. | permeability |
| B. | reluctance |
| C. | counter emf |
| D. | coefficient of coupling |
| Answer» B. reluctance | |
| 223. |
In a purely inductive circuit, |
| A. | current leads voltage by 90 |
| B. | voltage lags current by 90 |
| C. | voltage leads current by 90 |
| D. | voltage and current are in phase (0 ) |
| Answer» D. voltage and current are in phase (0 ) | |
| 224. |
List three diode packages: |
| A. | clip package, DIP, small current package |
| B. | DIP, small current package, large current package |
| C. | small current package, large current package, and SIP |
| D. | small current package, large current package, clip package |
| Answer» E. | |
| 225. |
The mimicking of an open/closed switch by a diode allows alternating current to be: |
| A. | rectified |
| B. | regulated |
| C. | controlled |
| D. | attenuated |
| Answer» B. regulated | |
| 226. |
With a half-wave rectified voltage across the load resistor, load current flows for what part of a cycle? |
| A. | 0 degrees |
| B. | 90 degrees |
| C. | 180 degrees |
| D. | 360 degrees |
| Answer» D. 360 degrees | |
| 227. |
Which of the following circuits would require the least amount of filtering? |
| A. | A half-wave rectifier |
| B. | A full-wave rectifier |
| C. | A bridge rectifier |
| D. | A full-wave rectifier and a bridge rectifier |
| Answer» E. | |
| 228. |
What is wrong with this circuit? |
| A. | The zener is open. |
| B. | The zener is shorted. |
| C. | nothing |
| D. | not enough data |
| Answer» B. The zener is shorted. | |
| 229. |
The voltage where current may start to flow in a reverse-biased pn junction is called the |
| A. | breakdown voltage |
| B. | barrier potential |
| C. | forward voltage |
| D. | biasing voltage |
| Answer» B. barrier potential | |
| 230. |
With a 12 V supply, a silicon diode, and a 370-ohm resistor in series, what voltage will be dropped across the diode? |
| A. | 0.3 V |
| B. | 0.7 V |
| C. | 0.9 V |
| D. | 1.4 V |
| Answer» C. 0.9 V | |
| 231. |
If the frequency of the applied ac signal to a half-wave rectifier is 60 Hz, the frequency of the pulsating dc output will be |
| A. | 30 pps |
| B. | 60 pps |
| C. | 90 pps |
| D. | 120 pps |
| Answer» C. 90 pps | |
| 232. |
What is the peak output voltage for this half-wave rectifier? |
| A. | 1 V |
| B. | 7.8 V |
| C. | 10.9 V |
| D. | 15.6 V |
| Answer» C. 10.9 V | |
| 233. |
Thermal shutdown occurs in an IC regulator if: |
| A. | power dissipation is too high |
| B. | internal temperature is too high |
| C. | current through the device is too high |
| D. | load resistance increases |
| Answer» C. current through the device is too high | |
| 234. |
The conduction band is closest to the valence band in |
| A. | semiconductors |
| B. | conductors |
| C. | insulators |
| D. | The distance is the same for all of the above. |
| Answer» B. conductors | |
| 235. |
DC power should be connected to forward bias a diode as follows: |
| A. | anode, + cathode |
| B. | cathode, anode |
| C. | + anode, cathode |
| D. | + cathode, + anode |
| Answer» D. + cathode, + anode | |
| 236. |
At any given time in an intrinsic piece of semiconductor material at room temperature |
| A. | electrons drift randomly |
| B. | recombination occurs |
| C. | holes are created |
| D. | All of the above |
| Answer» E. | |
| 237. |
What is the percent of regulation if Vnl = 20 V and Vfl = 19.8 V? |
| A. | 0% |
| B. | 1% |
| C. | .1% |
| D. | 5% |
| Answer» C. .1% | |
| 238. |
If the primary power of an ideal transformer having a 2:1 voltage ratio is 100 W, the secondary power is |
| A. | 100 W |
| B. | 50 W |
| C. | 75 W |
| D. | 200 W |
| Answer» B. 50 W | |
| 239. |
In a power supply diagram, which block indicates a pulsating dc output? |
| A. | transformer |
| B. | filter |
| C. | rectifier |
| D. | regulator |
| Answer» D. regulator | |
| 240. |
Providing a constant output regardless of ac input or load resistance changes is the function of a: |
| A. | transformer |
| B. | filter |
| C. | regulator |
| D. | rectifier |
| Answer» D. rectifier | |
| 241. |
When a diode is destroyed it has infinite impedance. When damaged by heat it will probably: |
| A. | short |
| B. | conduct more |
| C. | conduct less |
| D. | open |
| Answer» B. conduct more | |
| 242. |
A transformer has |
| A. | primary and secondary windings, both of which are considered inputs |
| B. | primary and secondary windings, both of which are considered outputs |
| C. | a primary winding used as an output and a secondary winding used as an input |
| D. | a primary winding used as an input and a secondary winding used as an output |
| Answer» E. | |
| 243. |
The transformer turns ratio determines |
| A. | the ratio of primary and secondary voltages |
| B. | the ratio of primary and secondary currents |
| C. | the reflected impedance |
| D. | all of the above |
| Answer» E. | |
| 244. |
A series RL filter circuit with an output across the inductor will result in what type of filtering? |
| A. | passing of the higher frequencies |
| B. | passing of the lower frequencies |
| C. | blocking of the higher frequencies |
| D. | blocking of a certain range of frequencies |
| Answer» B. passing of the lower frequencies | |
| 245. |
What is the total inductance in the given circuit? |
| A. | 160 mH |
| B. | 300 mH |
| C. | 900 mH |
| D. | 1700 mH |
| Answer» B. 300 mH | |
| 246. |
On a schematic, dashed lines between two vertical coils usually mean the transformer has: |
| A. | an air core |
| B. | an iron core |
| C. | a nonmetallic core |
| D. | a ferrite core |
| Answer» E. | |
| 247. |
A special transformer used to convert unbalanced signals to balanced signals is the |
| A. | balun |
| B. | autotransformer |
| C. | center-tapped transformer |
| D. | step-across transformer |
| Answer» B. autotransformer | |
| 248. |
What is the secondary voltage in the given circuit? |
| A. | 13.3 V rms in phase with the primary |
| B. | 120 V rms in phase with the primary |
| C. | 13.3 V rms out of phase with the primary |
| D. | 120 V rms out of phase with the primary |
| Answer» D. 120 V rms out of phase with the primary | |
| 249. |
Faraday's law states that the: |
| A. | direction of the induced voltage produces an opposition |
| B. | direction of an induced current produces an aiding effect |
| C. | emf depends on the rate of cutting flux |
| D. | emf is related to the direction of the current |
| Answer» D. emf is related to the direction of the current | |
| 250. |
A henry value divided by a circuit resistive value provides the: |
| A. | counter emf value |
| B. | induced voltage amplitude |
| C. | rise or decay time constant |
| D. | quality factor of the coil |
| Answer» C. rise or decay time constant | |