McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Electronics and Communication Engineering .
| 201. |
Consider a zener diode with a slope resistance of 10 Ω in series with a 90 Ω resistor fed from a dc supply containing a ripple voltage of 20mV peak-to-peak. Compute for the ripple voltage in load |
| A. | 1 mv p-p |
| B. | 2 mv p-p |
| C. | 1 v p-p |
| D. | 6mv p-p |
| Answer» B. 2 mv p-p | |
| 202. |
The of a common collector configuration is unity |
| A. | voltage gain |
| B. | current gain |
| C. | power gain |
| D. | input impedance |
| Answer» A. voltage gain | |
| 203. |
Transmit time is the time taken by the electrons on holes to pass from |
| A. | emitter to collector |
| B. | collector to emitter |
| C. | base to emitter |
| D. | base to collector |
| Answer» A. emitter to collector | |
| 204. |
Which amplifier is commonly used as a frequency multiplier? |
| A. | class a |
| B. | class b |
| C. | class c |
| D. | all of the above |
| Answer» C. class c | |
| 205. |
A class A amplifier has a voltage gain of 30 and a current gain of What is the power gain? |
| A. | 30 |
| B. | 25 |
| C. | 1.2 |
| D. | 750 |
| Answer» D. 750 | |
| 206. |
You have an application for a power amplifier to operate on FM radio frequencies. The most likely choice would be a amplifier. |
| A. | class a |
| B. | class b |
| C. | class c |
| D. | class ab |
| Answer» C. class c | |
| 207. |
A class A amplifier with RC = 3.3 kΩ and RE = 1.2 kΩ has a VCC = 20 V. Find IC(sat). |
| A. | 4.4 ma |
| B. | 6.1 ma |
| C. | 16.7 ma |
| D. | 20 ma |
| Answer» A. 4.4 ma | |
| 208. |
A class C amplifier has a tank circuit in the output. The amplifier is conducting only 28°. The output voltage is |
| A. | 0 v. |
| B. | a dc value equal to vcc. |
| C. | a sine wave. |
| D. | a square wave with a frequency determined by the tank. |
| Answer» C. a sine wave. | |
| 209. |
In practice, the efficiency of a capacitively coupled class A amplifier is about %. |
| A. | 25 |
| B. | 40 |
| C. | 70 |
| D. | 10 |
| Answer» D. 10 | |
| 210. |
The Q-point is at cutoff for class operation. |
| A. | a |
| B. | b |
| C. | c |
| D. | ab |
| Answer» B. b | |
| 211. |
Class amplifiers are normally operated in a push-pull configuration in order to produce an output that is a replica of the input. |
| A. | a |
| B. | b |
| C. | c |
| D. | ab |
| Answer» D. ab | |
| 212. |
The maximum efficiency of a class B amplifier is percent. |
| A. | 50 |
| B. | 25 |
| C. | 70 |
| D. | 79 |
| Answer» D. 79 | |
| 213. |
A class amplifier is biased slightly above cutoff and operates in the linear region for slightly more than 180º of the input cycle. |
| A. | a |
| B. | b |
| C. | c |
| D. | ab |
| Answer» D. ab | |
| 214. |
Which class of amplifier operates in the linear region for only a small part of the input cycle? |
| A. | a |
| B. | b |
| C. | c |
| D. | ab |
| Answer» C. c | |
| 215. |
The principal advantage(s) of MOSFETs over BJTs is (are) |
| A. | their biasing networks are simpler. |
| B. | their drive requirements are simpler. |
| C. | they can be connected in parallel for added drive capability. |
| D. | all of the above |
| Answer» D. all of the above | |
| 216. |
The principal advantage(s) of BJTs over MOSFETs is (are) that |
| A. | voltage drop across the transistor is important. |
| B. | they are not as prone to esd. |
| C. | both of the above |
| D. | none of the above |
| Answer» C. both of the above | |
| 217. |
The class amplifier is biased below cutoff. |
| A. | a |
| B. | ab |
| C. | b |
| D. | c |
| Answer» C. b | |
| 218. |
For Class-B operation, the collector current flows for |
| A. | the whole cycle |
| B. | half the cycle |
| C. | less than half a cycle |
| D. | less than a quarter of a cycle |
| Answer» B. half the cycle | |
| 219. |
Transformer coupling is an example of |
| A. | direct coupling |
| B. | ac coupling |
| C. | dc coupling |
| D. | impedance coupling |
| Answer» B. ac coupling | |
| 220. |
Class-C amplifiers are almost always |
| A. | transformer- coupled between stages |
| B. | operated at audio frequencies |
| C. | tuned rf amplifiers |
| D. | wideband |
| Answer» C. tuned rf amplifiers | |
| 221. |
Heat sinks reduce the |
| A. | transistor power |
| B. | ambient temperature |
| C. | junction temperature |
| D. | collector current |
| Answer» C. junction temperature | |
| 222. |
Which type of power amplifier is biased for operation at less than 180º of the cycle? |
| A. | class a |
| B. | class b or ab |
| C. | class c |
| D. | class d |
| Answer» C. class c | |
| 223. |
What is the maximum efficiency of a class A circuit with a direct or series-fed load connection? |
| A. | 90% |
| B. | 78.50% |
| C. | 50% |
| D. | 25% |
| Answer» D. 25% | |
| 224. |
The Q-point is at cutoff for class operation. |
| A. | a |
| B. | b |
| C. | c |
| D. | ab |
| Answer» B. b | |
| 225. |
Which of the following is (are) power amplifiers? |
| A. | class a |
| B. | class b or ab |
| C. | class c or d |
| D. | all of the above |
| Answer» D. all of the above | |
| 226. |
The output of a class-B amplifier |
| A. | is distortion free |
| B. | consists of positive half cycle only |
| C. | is like the output of a full wave rectifier |
| D. | comprises short duration current pulses |
| Answer» B. consists of positive half cycle only | |
| 227. |
Crossover distortion occurs in amplifiers. |
| A. | push-pull |
| B. | class a |
| C. | class b |
| D. | class ab |
| Answer» A. push-pull | |
| 228. |
The main use of a class C amplifier is |
| A. | as an rf amplifier |
| B. | as stereo amplifier |
| C. | in communication sound equipment |
| D. | as distortion generator |
| Answer» A. as an rf amplifier | |
| 229. |
The decibel is a measure of |
| A. | power |
| B. | voltage |
| C. | current |
| D. | sound level |
| Answer» D. sound level | |
| 230. |
The output stage of a multistage amplifier is also called |
| A. | mixer stage |
| B. | power stage |
| C. | detector stage |
| D. | f stage |
| Answer» B. power stage | |
| 231. |
coupling is generally employed in power amplifiers |
| A. | transformer |
| B. | rc |
| C. | direct |
| D. | impedance |
| Answer» A. transformer | |
| 232. |
The maximum efficiency of resistance loaded class A power amplifier is |
| A. | 5% |
| B. | 50% |
| C. | 30% |
| D. | 25% |
| Answer» D. 25% | |
| 233. |
Class power amplifier has the highest collector efficiency |
| A. | c |
| B. | a |
| C. | b |
| D. | ab |
| Answer» C. b | |
| 234. |
Power amplifiers handle signals compare to voltage amplifiers. |
| A. | small |
| B. | very small |
| C. | large |
| D. | none of the above |
| Answer» C. large | |
| 235. |
In class B operation, at what fraction of VCC should the level of VL(p) be to achieve the maximum power dissipated by the output transistor? |
| A. | 0.5 |
| B. | 0.636 |
| C. | 0.707 |
| D. | 1 |
| Answer» B. 0.636 | |
| 236. |
In class A operation, the operating point is generally located of the d.c. load line. |
| A. | at cut off point |
| B. | at the middle |
| C. | at saturation point |
| D. | none of the above |
| Answer» B. at the middle | |
| 237. |
The output transformer used in a power amplifier is a transformer. |
| A. | 1:1 ratio |
| B. | step-up |
| C. | step-down |
| D. | none of the above |
| Answer» C. step-down | |
| 238. |
Power amplifiers primarily provide sufficient power to an output load, typically from to . |
| A. | a few kw, tens of kw |
| B. | 500 w, 1 kw |
| C. | 100 w, 500 w |
| D. | a few w, tens of w |
| Answer» D. a few w, tens of w | |
| 239. |
The main feature(s) of a large-signal amplifier is (are) the . |
| A. | circuit\s power efficiency |
| B. | maximum amount of power that the circuit is capable of handling |
| C. | impedance matching to the output |
| D. | all of the above |
| Answer» D. all of the above | |
| 240. |
In power amplifiers, the output signal varies for a full 360º of the cycle. |
| A. | class a |
| B. | class b or ab |
| C. | class c |
| D. | class d |
| Answer» A. class a | |
| 241. |
In class B power amplifiers, the output signal varies for of the cycle. |
| A. | 360º |
| B. | 180º |
| C. | between 180º and 360º |
| D. | less than 180º |
| Answer» B. 180º | |
| 242. |
amplifiers have the highest overall efficiency. |
| A. | class a |
| B. | class b or ab |
| C. | class c |
| D. | class d |
| Answer» D. class d | |
| 243. |
Class D operation can achieve power efficiency of over . |
| A. | 90% |
| B. | 78.50% |
| C. | 50% |
| D. | 25% |
| Answer» A. 90% | |
| 244. |
The beta of a power transistor is generally . |
| A. | more than 200 |
| B. | 100 to 200 |
| C. | less than 100 |
| D. | 0 |
| Answer» C. less than 100 | |
| 245. |
A form of class A amplifier having maximum efficiency of _ uses a transformer to couple the output signal to the load. |
| A. | 90% |
| B. | 78.50% |
| C. | 50% |
| D. | 25% |
| Answer» C. 50% | |
| 246. |
The reflected impedance seen from one side of the transformer to the other side is . |
| A. | n1/n2 |
| B. | (n1/n2)2 |
| C. | (n1/n2)1/3 |
| D. | n1× n2 |
| Answer» B. (n1/n2)2 | |
| 247. |
In a class A transformer-coupled power amplifier, winding resistance of the transformer determine(s) the dc load line for the circuit. |
| A. | the ac |
| B. | the dc |
| C. | both the ac and dc |
| D. | neither the ac nor dc |
| Answer» B. the dc | |
| 248. |
The slope of the ac load line in the class A transformer-coupled transistor is . |
| A. | –1/rl (load resistor) |
| B. | 1/(a2rl) |
| C. | –1/(a2rl) |
| D. | 1/rl |
| Answer» C. –1/(a2rl) | |
| 249. |
The amount of power dissipated by the transistor is the of that drawn from the dc supply (set by the bias point) and the amount delivered to the ac load. |
| A. | product |
| B. | difference |
| C. | average |
| Answer» B. difference | |
| 250. |
A class A amplifier dissipates power when the load is drawing maximum power from the circuit. |
| A. | the least |
| B. | about the same |
| C. | the most |
| D. | none of the above |
| Answer» A. the least | |
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