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MCQOPTIONS
This section includes 1136 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 301. |
In a self bias circuit for CE amplifier, the emitter resistance is made three times the original value. The collector current will |
| A. | remain the same |
| B. | become three times |
| C. | decrease |
| D. | become one-third |
| Answer» E. | |
| 302. |
In a full wave voltage doubler circuit, the input frequency is 560 Hz. The ripple frequency is |
| A. | 25 Hz |
| B. | 50 Hz |
| C. | 100 Hz |
| D. | 200 Hz |
| Answer» D. 200 Hz | |
| 303. |
In an amplifier with a gain of - 1000 and feedback factor β = - 0.1, the change in gain is 20% due to temperature. The change in gain for feedback amplifier will be |
| A. | 0.1 |
| B. | 0.05 |
| C. | 0.002 |
| D. | 0.0001 |
| Answer» D. 0.0001 | |
| 304. |
Figure shows the feedback network of one of the very popular types of sinusoidal oscillators. Which one is that? |
| A. | Weinbridge oscillator |
| B. | Hartley oscillator |
| C. | Colpitt's oscillator |
| D. | R-C phase shift oscillator |
| Answer» B. Hartley oscillator | |
| 305. |
In a CE amplifier circuit the load resistance is open circuited. The output voltage will |
| A. | increase |
| B. | decrease |
| C. | become zero |
| D. | increase or decrease |
| Answer» B. decrease | |
| 306. |
For high frequency response of a transistor amplifier, suitable model to use is |
| A. | Kelvin network |
| B. | Lattice network |
| C. | Hybrid p |
| D. | T-network |
| Answer» D. T-network | |
| 307. |
For CE amplifier of figure, the slope of ac load line is |
| A. | |
| B. | |
| Answer» B. | |
| 308. |
Wide banding technique is employed in the |
| A. | RF amplifier of an AM receiver |
| B. | input section of a communication receiver |
| C. | Both A and R are correct and R is correct explanation for A |
| D. | Both A and R are correct but R is not correct explanation for A |
| Answer» B. input section of a communication receiver | |
| 309. |
Percentage increase in the reverse saturation current of a diode if the temperature is increased from 25°C to 50°C |
| A. | 0.5 |
| B. | 5 |
| C. | 5.657 |
| D. | 5.756 |
| Answer» D. 5.756 | |
| 310. |
A transistor will operate in inverted region when |
| A. | emitter junction is forward biased and collector junction is reverse biased |
| B. | emitter junction is reverse biased and collector junction is forward biased |
| C. | emitter junction as well as collector junction are forward biased |
| D. | emitter junction as well as collector junction are reverse biased |
| Answer» C. emitter junction as well as collector junction are forward biased | |
| 311. |
As compared to a bipolar transistor, a JFET is |
| A. | less sensitive to changes in input voltage |
| B. | equally sensitive to changes in input voltage |
| C. | increase the base storage charge |
| D. | provide ac coupling |
| Answer» D. provide ac coupling | |
| 312. |
The PIV of a bridge rectifier is less than that of full wave rectifier with centre tapped transformer. |
| A. | 1 |
| B. | |
| C. | D MOSFETs |
| D. | E MOSFETs |
| Answer» B. | |
| 313. |
In a FET, gm varies as |
| A. | IDS |
| B. | IDS2 |
| C. | 1/IDS |
| D. | IDS |
| Answer» E. | |
| 314. |
Generally the gain of a transistor amplifier falls at high frequencies due to the |
| A. | internal capacitance of device |
| B. | coupling capacitor at the I/P |
| C. | skin effect |
| D. | coupling capacitor at the O/P |
| Answer» B. coupling capacitor at the I/P | |
| 315. |
A transistor may fail due to |
| A. | open weld at the wire leads to the semi-conductor |
| B. | short circuit caused by momentary overloads |
| C. | overheating due to circuit failures |
| D. | any of the above |
| Answer» E. | |
| 316. |
Which of the following configuration has low thermal stability? |
| A. | CB |
| B. | CC |
| C. | CE |
| D. | All have identical thermal stability |
| Answer» B. CC | |
| 317. |
Typical values of voltage gain for CE, CB and CC amplifiers are |
| A. | 100, 100 and 1 respectively |
| B. | 100, 1 and 100 respectively |
| C. | 100, 1 and 1 respectively |
| D. | 1, 100 and 100 respectively |
| Answer» B. 100, 1 and 100 respectively | |
| 318. |
The minimum value of hfe of a transistor used in RC phase shift oscillator is |
| A. | 54.4 |
| B. | 45.4 |
| C. | 44.5 |
| D. | 29 |
| Answer» D. 29 | |
| 319. |
In the circuit of figure, PIV can be up to |
| A. | 0.5 Em |
| B. | 2 Em |
| Answer» C. | |
| 320. |
Assertion (A): In class C amplifier the efficiency is more than that for other classes of amplifiersReason (R): In class C amplifier we can get high efficiency over a wideband |
| A. | Both A and R are correct and R is correct explanation for A |
| B. | Both A and R are correct but R is not correct explanation for A |
| C. | A is correct R is wrong |
| D. | A is wrong R is correct |
| Answer» D. A is wrong R is correct | |
| 321. |
If input frequency is 50 Hz, the frequency of output wave in a half wave diode rectifier circuit is |
| A. | 25 Hz |
| B. | 50 Hz |
| C. | 100 Hz |
| D. | 200 Hz |
| Answer» C. 100 Hz | |
| 322. |
The stray capacitance between the last stage and the first stage of an oscillator may cause |
| A. | unwanted oscillations at low and high frequencies |
| B. | large feedback |
| C. | zener current is very small |
| D. | zener current is very large |
| Answer» C. zener current is very small | |
| 323. |
In a transistor βdc is likely to vary between 100 and 400. The proper value of βdc to be used to located Q point is |
| A. | Shot noise |
| B. | Agitation noise |
| C. | Flicker noise |
| D. | Transit time noise |
| Answer» E. | |
| 324. |
A three-section RC phase shift oscillator has R = 10K ohms and C = 0.001 μF. If the oscillator is to be made variable using the same value of R, what should be the value of capacitor to obtain a frequency if 1 kHz? |
| A. | 636 pF |
| B. | 180 pF |
| C. | 65 pF |
| D. | 30 pF |
| Answer» D. 30 pF | |
| 325. |
An engineer designs an amplifier to have a voltage gain of 60, but when constructed it only had a gain of 50. What value of feedback will double the gain? |
| A. | 0.01 |
| B. | 0.033 |
| C. | 0.125 |
| D. | 0.25 |
| Answer» D. 0.25 | |
| 326. |
In the self biasing scheme (RF across collector to base) of BJT, S1 tends to unity by __________ RC is the collector load Resistance. |
| A. | increasing RF |
| B. | decreasing RF |
| C. | decreasing RF and increasing RC |
| D. | increasing RF and decreasing RC |
| Answer» D. increasing RF and decreasing RC | |
| 327. |
In the graphical analysis of CE amplifier circuit, the upper end of load line is called |
| A. | 220 V |
| B. | 200 V |
| C. | 198 V |
| D. | 0 volts |
| Answer» B. 200 V | |
| 328. |
Oscillation of frequency in Hartley oscillator is |
| A. | |
| B. | |
| Answer» C. | |
| 329. |
Figure shows a portion of linear v - i characteristics of diode. If applied voltage is + 6 V, the current will be |
| A. | 51 mA |
| B. | 54 mA |
| C. | 80°C |
| D. | 20°C |
| Answer» E. | |
| 330. |
A multistage amplifier has a low pass response with three real poles at s = - w1 - w2 and w3. The approximate overall bandwidth B of the amplifier will be given by |
| A. | B = w1 + w2 + w3 |
| B. | |
| C. | B = (w1 + w2 + w3)1/3 |
| Answer» B. | |
| 331. |
The open loop gain of an ideal op-amp is |
| A. | infinite |
| B. | very high |
| C. | neither high nor low |
| D. | low |
| Answer» B. very high | |
| 332. |
Each of two cascaded stages has a voltage gain of 30. The overall gain is |
| A. | 3 |
| B. | 9 |
| C. | 30 |
| D. | 900 |
| Answer» E. | |
| 333. |
Assertion (A): In a common source amplifier with source terminal at ac ground the voltage gain is about gm rdReason (R): A common source amplifier is a source follower circuit |
| A. | Both A and R are correct and R is correct explanation for A |
| B. | Both A and R are correct but R is not correct explanation for A |
| C. | A is correct R is wrong |
| D. | A is wrong R is correct |
| Answer» D. A is wrong R is correct | |
| 334. |
In figure which diode will conduct and what will be the value of V0? |
| A. | D3, 1 V |
| B. | D1, 2 V |
| C. | D2, 5 V |
| D. | D1, 5 V |
| Answer» D. D1, 5 V | |
| 335. |
Assertion (A): In Darlington pair, the overall β is product of individual βsReason (R): The voltage gain of a base driven amplifier is equal to ac collector voltage divided by ac base voltage |
| A. | Both A and R are correct and R is correct explanation for A |
| B. | Both A and R are correct but R is not correct explanation for A |
| C. | A is correct R is wrong |
| D. | A is wrong R is correct |
| Answer» C. A is correct R is wrong | |
| 336. |
A difference amplifier using op-amp has closed loop gain = 50. If input is 2 V to each of inverting and non-inverting terminals, output is 5 mA. Then CMRR = |
| A. | 20000 |
| B. | 2000 |
| C. | 200 |
| D. | 20 |
| Answer» B. 2000 | |
| 337. |
A rectifier circuit has load resistance R. It uses a capacitance filter having capacitance C. For low ripple in the output |
| A. | RC should be 1 |
| B. | RC should be low |
| C. | RC should be high |
| D. | RC should be neither low nor high |
| Answer» D. RC should be neither low nor high | |
| 338. |
In which configuration is ac collector voltage zero? |
| A. | CE |
| B. | CB |
| C. | CC |
| D. | none of the above |
| Answer» D. none of the above | |
| 339. |
In case of a transistor amplifier the emitter resistance Re is removed |
| A. | the gain of the amplifier will reduce |
| B. | heat sink will not be required |
| C. | Q-point will become unstable |
| D. | base to emitter function will be less forward biased |
| Answer» D. base to emitter function will be less forward biased | |
| 340. |
In a half wave diode rectifier circuit the current flows in the load circuit for |
| A. | 270° in each cycle |
| B. | 360° in each cycle |
| C. | each transistor conducts for 180° |
| D. | each transistor conducts for more than 180° but less than 360° |
| Answer» C. each transistor conducts for 180¬∞ | |
| 341. |
For the circuit of figure the input and output Miller resistances are |
| A. | 5 kΩ and 1 ohm respectively |
| B. | 1 ohm each |
| C. | its reactance is small for the lowest frequency in the input and output |
| D. | its reactance is high for the lowest frequency in the input and output |
| Answer» C. its reactance is small for the lowest frequency in the input and output | |
| 342. |
The dc output voltage of the circuit is |
| A. | 4.3 V |
| B. | 1.369 V |
| C. | 3.87 V |
| D. | 1.94 V |
| Answer» C. 3.87 V | |
| 343. |
The most widely used diode rectifier circuit is |
| A. | half wave |
| B. | full wave with centre tapped transformer |
| C. | bridge |
| D. | either (a) or (b) |
| Answer» D. either (a) or (b) | |
| 344. |
The mobility of e- for Ge and Si respectively is |
| A. | 1.66, 2.5 |
| B. | 2.5, 1.66 |
| C. | 2.7, 2.33 |
| D. | 2.33, 2.7 |
| Answer» B. 2.5, 1.66 | |
| 345. |
In figure if the transistor is cut off, the collector voltage is equal to |
| A. | VCC |
| B. | 0.5 VCC |
| C. | |
| Answer» B. 0.5 VCC | |
| 346. |
The theoretical maximum efficiency of a half wave diode rectifier is |
| A. | 0.406 |
| B. | 0.5 |
| C. | 0.812 |
| D. | slightly less than 100% |
| Answer» B. 0.5 | |
| 347. |
In the circuit shown in figure, RC = 10k, RE = 150Ω, β = 100, I = 1 mA. The value of , will be |
| A. | 50 |
| B. | 100 |
| C. | 192 |
| D. | 400 |
| Answer» D. 400 | |
| 348. |
Assertion (A): A Darlington amplifier has very low output impedanceReason (R): The circuit has a low resistance RE between emitter and ground |
| A. | A is correct R is wrong |
| B. | A is wrong R is correct |
| C. | a tapped inductor |
| D. | a tapped capacitor |
| Answer» D. a tapped capacitor | |
| 349. |
In a resistance loaded, RC coupled amplifier the d.c. component is blocked by |
| A. | Transistor |
| B. | CC |
| C. | RB |
| D. | RC |
| Answer» C. RB | |
| 350. |
The common emitter short circuit current gain β of a transistor |
| A. | is a monotonically increasing function of the collector current Ic |
| B. | is a monotonically decreasing function of Ic |
| C. | increasing with Ic, for low Ic, reaches a maximum and then decreases with further increase in Ic |
| D. | is not a function of Ic |
| Answer» D. is not a function of Ic | |