McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Electronics and Communication Engineering .
| 251. |
In a class A transformer-coupled amplifier, the the value of VCEmax and the the value of VCEmin, the the efficiency to (from) the theoretical limit of 50%. |
| A. | larger, smaller, farther |
| B. | larger, smaller, closer |
| C. | smaller, larger, closer |
| D. | none of the above |
| Answer» B. larger, smaller, closer | |
| 252. |
In class B operation, the current drawn from a single power supply has the form of rectified signal. |
| A. | a full-wave |
| B. | a half-wave |
| C. | both a full-wave and a half-wave |
| D. | none of the above |
| Answer» A. a full-wave | |
| 253. |
The highest efficiency is obtained in class B operation when the level of VL(p) is equal to . |
| A. | 0.25vcc |
| B. | 0.50vcc |
| C. | vcc |
| D. | 2vcc |
| Answer» C. vcc | |
| 254. |
transistors can be used to build a class B amplifier. |
| A. | npn and pnp |
| B. | nmos and pmos |
| C. | both npn and pnp or nmos and pmos |
| D. | none of the above |
| Answer» C. both npn and pnp or nmos and pmos | |
| 255. |
The complementary Darlington-connected transistor for a class B amplifier provides output current and output resistance. |
| A. | higher, higher |
| B. | higher, lower |
| C. | lower, lower |
| D. | lower, higher |
| Answer» B. higher, lower | |
| 256. |
The fundamental component is typically any harmonic component. |
| A. | larger than |
| B. | the same as |
| C. | smaller than |
| D. | none of the above |
| Answer» A. larger than | |
| 257. |
In Fourier technique, any periodic distorted waveform can be represented by the fundamental and all harmonic components. |
| A. | multiplying |
| B. | subtracting |
| C. | dividing |
| D. | adding |
| Answer» D. adding | |
| 258. |
Improvement in production techniques of power transistors have . |
| A. | produced higher power ratings in small-sized packaging cases |
| B. | increased the maximum transistor breakdown voltage |
| C. | provided faster- switching power transistors |
| D. | all of the above |
| Answer» D. all of the above | |
| 259. |
The greater the power handled by the power transistor, the |
| A. | the higher |
| B. | the lower |
| C. | there is no |
| D. | none of the above |
| Answer» A. the higher | |
| 260. |
The has the hottest temperature in a power transistor. |
| A. | heat sink |
| B. | case |
| C. | junction |
| D. | none of the above |
| Answer» C. junction | |
| 261. |
A heat sink provides thermal resistance between case and air. |
| A. | a high |
| B. | a low |
| C. | the same |
| D. | none of the above |
| Answer» B. a low | |
| 262. |
A power amplifier is limited to use at one fixed frequency. |
| A. | class a |
| B. | class b or ab |
| C. | class c |
| D. | class d |
| Answer» C. class c | |
| 263. |
By how much does the output signal vary for a class AB power amplifier? |
| A. | 360º |
| B. | 180º |
| C. | between 180º and 360º |
| D. | less than 180º |
| Answer» C. between 180º and 360º | |
| 264. |
Which type of amplifier uses pulse (digital) signals in its operation? |
| A. | class a |
| B. | class b or ab |
| C. | class c |
| D. | class d |
| Answer» D. class d | |
| 265. |
Which of the power amplifiers has the lowest overall efficiency? |
| A. | class a |
| B. | class b or ab |
| C. | class c |
| D. | class d |
| Answer» A. class a | |
| 266. |
Which of the following describe(s) a power amplifier? |
| A. | it can handle large power. |
| B. | it can handle large current. |
| C. | it does not provide much voltage gain. |
| D. | all of the above |
| Answer» D. all of the above | |
| 267. |
amplifiers primarily provide sufficient power to an output load to drive a speaker from a few watts to tens of watts. |
| A. | small-signal |
| B. | power |
| C. | none of the above |
| D. | all of the above |
| Answer» B. power | |
| 268. |
The main features of a large-signal amplifier is the circuit's . |
| A. | power efficiency |
| B. | maximum power limitations |
| C. | impedance matching to the output device |
| D. | all of the above |
| Answer» D. all of the above | |
| 269. |
Categorize the power efficiency of each class of amplifier, from worst to best. |
| A. | a, b, ab, d |
| B. | a, ab, d, b |
| C. | a, ab, b, d |
| Answer» C. a, ab, b, d | |
| 270. |
What is the ratio of the secondary voltage to the primary voltage with the turn ratio in the winding |
| A. | n2/n1 |
| B. | (n1/n2)2 |
| C. | (n1/n2)1/3 |
| D. | n1 × n2 |
| Answer» A. n2/n1 | |
| 271. |
Calculate the effective resistance seen looking into the primary of a 20:1 transformer connected to an 8- Ω load. |
| A. | 3.2 kΩ |
| B. | 3.0 kΩ |
| C. | 2.8 kΩ |
| D. | 1.8 kΩ |
| Answer» A. 3.2 kΩ | |
| 272. |
What transformer turns ratio is required to match an 8-speaker load so that the effective load resistance seen at the primary is 12.8 k? |
| A. | 20:01 |
| B. | 40:01:00 |
| C. | 50:01:00 |
| D. | 60:01:00 |
| Answer» B. 40:01:00 | |
| 273. |
Calculate the efficiency of a transformer-coupled class A amplifier for a supply of 15 V and an output of V(p) = 10 V. |
| A. | 25% |
| B. | 33.30% |
| C. | 50% |
| D. | 78.50% |
| Answer» B. 33.30% | |
| 274. |
The maximum efficiency of a transformer-coupled class A amplifier is . |
| A. | 25% |
| B. | 50% |
| C. | 78.5% |
| D. | 63.6% |
| Answer» B. 50% | |
| 275. |
How many transistors must be used in a class B power amplifier to obtain the output for the full cycle of the signal? |
| A. | 0 |
| B. | 1 |
| C. | 2 |
| D. | 3 |
| Answer» C. 2 | |
| 276. |
Class B operation is provided when the dc bias leaves the transistor biased just off, the transistor turning on when the ac signal is applied. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 277. |
Calculate the efficiency of a class B amplifier for a supply voltage of VCC = 20 V with peak output voltage of VL(p) = 18 V. Assume RL = 16 Ω. |
| A. | 78.54% |
| B. | 75% |
| C. | 70.69% |
| D. | 50% |
| Answer» C. 70.69% | |
| 278. |
Which of the following is (are) the disadvantage(s) of a class B complementary-symmetry circuit? |
| A. | it needs two separate voltage sources. |
| B. | there is crossover distortion in the output signal. |
| C. | it does not provide exact switching of one transistor off and the other on at the zero- voltage condition. |
| D. | all of the above |
| Answer» D. all of the above | |
| 279. |
nMOS and pMOS transistors can be used for class B. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 280. |
Calculate the harmonic distortion component for an output signal having fundamental amplitude of 3 V and a second harmonic amplitude of 0.25 V. |
| A. | 3.83% |
| B. | 38.3% |
| C. | 83.3% |
| D. | 8.33% |
| Answer» D. 8.33% | |
| 281. |
Which of the following instruments displays the harmonics of a distorted signal? |
| A. | digital multimeter |
| B. | spectrum analyzer |
| C. | oscilloscope |
| D. | wave analyzer |
| Answer» B. spectrum analyzer | |
| 282. |
Which of the following instruments allows more precise measurement of the harmonic components of a distorted signal? |
| A. | digital multimeter |
| B. | spectrum analyzer |
| C. | oscilloscope |
| D. | wave analyzer |
| Answer» D. wave analyzer | |
| 283. |
What is the maximum temperature rating for silicon power transistors? |
| A. | 50º to 80º |
| B. | 100º to 110º |
| C. | 150º to 200º |
| D. | 250º to 300º |
| Answer» C. 150º to 200º | |
| 284. |
Which of the power amplifiers is not intended primarily for large- signal or power amplification? |
| A. | class a |
| B. | class b or ab |
| C. | class c |
| D. | class d |
| Answer» C. class c | |
| 285. |
Determine what maximum dissipation will be allowed for a 70-W silicon transistor (rated at 25ºC) if derating is required above 25ºC by a derating factor of 0.6 W/ºC at a case temperature of 100º. |
| A. | 25 w |
| B. | 30 w |
| C. | 35 w |
| D. | 40 w |
| Answer» A. 25 w | |
| 286. |
A silicon power transistor is operated with a heat sink (θSA = 1.5ºC/W). The transistor, rated at 150 W (25ºC), has θJC = 0.5º C/W, and the mounting insulation has θCS = 0.6 ºC/W. What is the maximum power that can be dissipated if the ambient temperature is 50ºC and TJmax = 200 ºC? |
| A. | 61.5 w |
| B. | 60.0 w |
| C. | 57.7 w |
| D. | 55.5 w |
| Answer» C. 57.7 w | |
| 287. |
Which of the following transistors has been quite popular as the driver device for class D amplification? |
| A. | bjt |
| B. | fet |
| C. | ujt |
| D. | mosfet |
| Answer» D. mosfet | |
| 288. |
Kirchhoff's Voltage Law states that the total voltage around a closed loop must be |
| A. | 0 |
| B. | ½ |
| C. | 1 |
| D. | 2 |
| Answer» A. 0 | |
| 289. |
The algebraic sum of in a network of conductors meeting at a point is zero. |
| A. | voltages |
| B. | currents |
| C. | resistances |
| D. | inductances |
| Answer» B. currents | |
| 290. |
The theorem is a way to determine the currents and voltages present in a circuit that has multiple sources. |
| A. | norton |
| B. | super position |
| C. | thevenin |
| D. | maximum power transfer |
| Answer» B. super position | |
| 291. |
The concept on which Superposition theorem is based is |
| A. | reciprocity |
| B. | duality |
| C. | non-linearity |
| D. | linearity |
| Answer» D. linearity | |
| 292. |
Kirchhoff’s current law is applicable to only |
| A. | junction in a network |
| B. | closed loops in a network |
| C. | electric circuits |
| D. | electronic circuits |
| Answer» A. junction in a network | |
| 293. |
Kirchhoff's voltage law is related to |
| A. | junction currents |
| B. | battery emfs |
| C. | ir drops |
| D. | both b & c |
| Answer» D. both b & c | |
| 294. |
Superposition theorem can be applied only to circuits having |
| A. | resistive elements |
| B. | passive elements |
| C. | non-linear elements |
| D. | linear bilateral elements |
| Answer» D. linear bilateral elements | |
| 295. |
The concept on which superposition theorem is based on |
| A. | reciprocity |
| B. | duality |
| C. | non-linearity |
| D. | linearity |
| Answer» D. linearity | |
| 296. |
Node analysis can be applied for |
| A. | planar networks |
| B. | non-planar networks |
| C. | both a & b |
| D. | electric networks |
| Answer» C. both a & b | |
| 297. |
Mesh analysis is applicable for |
| A. | planar networks |
| B. | non-planar networks |
| C. | both a & b |
| D. | electric networks |
| Answer» A. planar networks | |
| 298. |
The superposition theorem is applicable to |
| A. | voltage only |
| B. | current only |
| C. | current and voltage |
| D. | current, voltage and power |
| Answer» D. current, voltage and power | |
| 299. |
Kirchhoff’s current law is applicable only to |
| A. | junction in a network |
| B. | closed loops in a network |
| C. | electric circuits |
| D. | electronic circuits |
| Answer» A. junction in a network | |
| 300. |
Maximum power output is obtained from a network when the load resistance is equal to the output resistance of the network as seen from the terminals of the load". The above statement is associated with |
| A. | mill man’s theorem |
| B. | thevenin\s theorem |
| C. | superposition theorem |
| D. | maximum power transfer theorem |
| Answer» D. maximum power transfer theorem | |
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