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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.
| 401. |
As a compared to a CB amplifier, a CE amplifier has |
| A. | lower input resistance |
| B. | higher input resistance |
| C. | unwanted low frequency oscillations |
| D. | unwanted high frequency oscillations |
| Answer» C. unwanted low frequency oscillations | |
| 402. |
In calculating input impedance, the load impedance is considered to be connected at the output. |
| A. | 100 |
| B. | 400 |
| C. | 250 |
| D. | 200 |
| Answer» B. 400 | |
| 403. |
The input voltage for starting oscillations in an oscillator is caused by |
| A. | negative feedback |
| B. | positive feedback |
| C. | noise voltage in resistors |
| D. | a special generator |
| Answer» D. a special generator | |
| 404. |
3N 200 is a |
| A. | dual gate MOSFET |
| B. | UJT |
| C. | 5.05 Ω |
| D. | 50.5 Ω |
| Answer» D. 50.5 Œ© | |
| 405. |
Assertion (A): A dc stabilizer has constant output voltage irrespective of variations in input voltage and load currentReason (R): A dc series regulator uses a zener diode across the load to stabilize the output 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 | |
| 406. |
In a CE amplifier, the output voltage is equal to product of |
| A. | ac collector current and ac collector resistance |
| B. | ac base current and ac collector resistance |
| C. | ac emitter current and ac emitter resistance |
| D. | ac collector current and source resistance |
| Answer» B. ac base current and ac collector resistance | |
| 407. |
A push pull amplifier is a |
| A. | power amplifier |
| B. | voltage amplifier |
| C. | current amplifier |
| D. | both power and current amplifier |
| Answer» B. voltage amplifier | |
| 408. |
Higher order active filters are used for variable |
| A. | bandwidth |
| B. | gain in the pass band |
| C. | impedance |
| D. | roll off rate |
| Answer» E. | |
| 409. |
In following circuit, RB will be if VCC = 10 V, VS = 2 V, RC = 5 kΩ, RS = 90 kΩ, β = 50, ICE = 0, VCEsat = 0.1 V |
| A. | 230 K |
| B. | 235 K |
| C. | 240 K |
| D. | 250 K |
| Answer» C. 240 K | |
| 410. |
If the midband gain of an amplifier is 40 dB, the gain at half power frequency is |
| A. | 37 dB |
| B. | 30 dB |
| C. | 20 dB |
| D. | 13 dB |
| Answer» B. 30 dB | |
| 411. |
In a transistor E mode the collector current with the transistor in cut off region is |
| A. | zero |
| B. | high |
| C. | equal to saturated value |
| D. | none of the above |
| Answer» B. high | |
| 412. |
The source of the harmonic distortion in a RC coupled transistor amplifier is usually |
| A. | power supply |
| B. | capacitor |
| C. | R-C circuit |
| D. | transistor |
| Answer» E. | |
| 413. |
A dc amplifier can operate |
| A. | at zero frequency |
| B. | only at low frequency |
| C. | only at high frequencies |
| D. | both at low and high frequencies |
| Answer» B. only at low frequency | |
| 414. |
If a common emitter amplifier with an emitter resistance RC has an overall transconductance gain of 1 m A/V, a voltage gain of - 4 and desensitivity of 50, then the value of the emitter resistance R would be |
| A. | 50 kΩ |
| B. | 0.98 kΩ |
| C. | 50 Ω |
| D. | 0.98 Ω |
| Answer» C. 50 Œ© | |
| 415. |
In following figure find VGG by assuming gate current is negligible for the p-channel JFET. (if IDQ = - 6 mA, RS = 0, VDD = -18 V, RD = 2 kΩ, IDSS = - 10 mA, IPO = - 3 V) |
| A. | 0.67 V |
| B. | 6.7 V |
| C. | 7 V |
| D. | 0.3 V |
| Answer» B. 6.7 V | |
| 416. |
Ebers Moll model is applicable to |
| A. | bipolar Junction transistor |
| B. | N MOS transistor |
| C. | unipolar junction transistor |
| D. | field effect transistor |
| Answer» B. N MOS transistor | |
| 417. |
Consider the following statementsA totem pole configuration used in the output stage if an op-amp has the advantage of using Only n-p-n BJTsComplementary symmetrical pair of transistorsOnly one transistor Which of these statements is/are correct? |
| A. | 1 alone |
| B. | 2 alone |
| C. | 3 alone |
| D. | 1 and 3 |
| Answer» B. 2 alone | |
| 418. |
RECTIFIER : OSCILLATOR :: |
| A. | Capacitance : Inductance |
| B. | Series resonance : Parallel resonance |
| C. | DC : AC |
| D. | Regulation : Efficiency |
| Answer» E. | |
| 419. |
A CE amplifier has re = 6 Ω, β = 100 and a = 0.98. The input impedance is |
| A. | 6 Ω |
| B. | 100 Ω |
| C. | 600 Ω |
| D. | 98 Ω |
| Answer» D. 98 Œ© | |
| 420. |
Which of the following represents the equivalent circuit of a crystal for crystal oscillator? |
| A. | Figure A |
| B. | Figure B |
| C. | Figure C |
| D. | None of the above |
| Answer» D. None of the above | |
| 421. |
n-channel MOS is |
| A. | slower than p-channel MOS |
| B. | faster than p-channel MOS |
| C. | same as p-channel MOS |
| D. | none of these |
| Answer» C. same as p-channel MOS | |
| 422. |
In figure the cut in voltage of diode is 0.7 V and its bulk resistance is 20 Ω. The peak value of circuit current of during positive and negative half cycles are |
| A. | 10 mA and zero |
| B. | 9.12 mA and zero |
| C. | 9.3 mA and zero |
| D. | zero and 9.12 mA |
| Answer» C. 9.3 mA and zero | |
| 423. |
For a transistor to have-a larger β it must have and a |
| A. | close to zero |
| B. | close to 0.5 |
| C. | close to unity |
| D. | nearly infinite |
| Answer» D. nearly infinite | |
| 424. |
In an op-amp a common mode signal is applied to |
| A. | inverting terminal |
| B. | non-inverting terminal |
| C. | both terminals |
| D. | one or both the terminals |
| Answer» D. one or both the terminals | |
| 425. |
The input to integrating op-amp is a rectangular wave. The output will be |
| A. | a sine wave |
| B. | a rectangular wave |
| C. | a triangular wave |
| D. | none of the above |
| Answer» D. none of the above | |
| 426. |
When a JFET is cut off, it's like an __________ switch and when it is saturated, it's like a __________ switch. |
| A. | closed, open |
| B. | open, closed |
| C. | open, open |
| D. | closed, closed |
| Answer» C. open, open | |
| 427. |
In figure the diode is ideal (zero cut in voltage zero forward resistance). Then the current through diode is |
| A. | 0 |
| B. | 0.16666666666667 |
| C. | 0.041666666666667 |
| D. | none of the above |
| Answer» D. none of the above | |
| 428. |
The voltage gain of an amplifier without and with feedback are 100 and 20. The negative feedback is |
| A. | 0.04 |
| B. | 0.05 |
| C. | 0.2 |
| D. | 0.8 |
| Answer» B. 0.05 | |
| 429. |
Figure shows a |
| A. | JFET |
| B. | n-channel MOSFET |
| C. | p-channel MOSFET |
| D. | none of the above |
| Answer» C. p-channel MOSFET | |
| 430. |
A transistor has a maximum power dissipation of 350 mW at an ambient temperature of 25°C. If derating factor is 2 mW/°C, the maximum power dissipation for 40°C ambient temperature is |
| A. | 300 mW |
| B. | 330 mW |
| C. | 350 mW |
| D. | 380 mW |
| Answer» D. 380 mW | |
| 431. |
For the high-pass circuit to act as a differentiator, the time constant must be |
| A. | small |
| B. | very small in comparison to the time period of the input signal |
| C. | very high in comparison to the time period of the input signal (that is low pass circuit) |
| D. | moderate value |
| Answer» C. very high in comparison to the time period of the input signal (that is low pass circuit) | |
| 432. |
The voltage eo indicated in the figure has been measured by an ideal voltmeter. Which of the following can be calculated? |
| A. | Input offset current only |
| B. | Both the bias currents and the I/P offset current |
| C. | lower RL is provided |
| D. | more bias is used |
| Answer» D. more bias is used | |
| 433. |
In a JFET, the lower end is called the __________ and the upper end is called the __________ . |
| A. | source, drain |
| B. | drain source |
| C. | UJT |
| D. | MOSFET |
| Answer» D. MOSFET | |
| 434. |
Which of the following plot can be used to show the input volt-ampere characteristics of a common-emitter configuration? |
| A. | VBE versus iB for constant values of VCE |
| B. | VCE versus iC for constant values of IB |
| C. | VCE versus iC for constant values of IE |
| D. | None of the above |
| Answer» B. VCE versus iC for constant values of IB | |
| 435. |
The approximate value of input impedance of a common emitter amplifier with emitter resistance Re is given by |
| A. | hie + AI Re |
| B. | hie + (i + hfe) Re |
| C. | hie |
| D. | (1 + hfe) Re |
| Answer» C. hie | |
| 436. |
Assertion (A): Negative feedback reduces the gain of an amplifierReason (R): Negative feedback is very commonly used in amplifier circuits |
| 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 | |
| 437. |
Feedback factor may be less or more than 1. |
| A. | 1 |
| B. | |
| C. | one RC combination |
| D. | two RC combinations |
| Answer» C. one RC combination | |
| 438. |
Which of the following method cannot be used to increase the bandwidth for cascaded RF amplifier stages? |
| A. | Wave traps in each stage |
| B. | Stagger tuning |
| C. | A shunt damping resistor across each tuned circuit |
| D. | Doubled tuned transformers with tighter coupling |
| Answer» B. Stagger tuning | |
| 439. |
In a P-N-P transistor, with normal bias |
| A. | the collector junction has negligible resistance |
| B. | only holes cross the collector junction |
| C. | the collector-base junction is reverse biased and the emitter base junction is forward biased |
| D. | only majority carriers cross the collector junction |
| Answer» D. only majority carriers cross the collector junction | |
| 440. |
In which amplifier circuit is gate conductance negligible? |
| A. | Both JFET and MOSFET amplifier |
| B. | None of the above |
| C. | VCC |
| D. | 0.5 VCC |
| Answer» C. VCC | |
| 441. |
From a measurement of the rise time of the output pulse of an amplifier whose input is a small amplitude square wave, one can estimate the following parameter of the amplifier |
| A. | gain bandwidth product |
| B. | slew rate |
| C. | upper 3 dB frequency |
| D. | lower 3 dB frequency |
| Answer» D. lower 3 dB frequency | |
| 442. |
The value of parameter re used in re transistor model |
| A. | increases with increase in temperature |
| B. | decreases with increase in temperature |
| C. | is not affected by increase in temperature |
| D. | either (b) or (c) |
| Answer» B. decreases with increase in temperature | |
| 443. |
By connecting external resistances to a differential amplifier we can adjust |
| A. | voltage gain |
| B. | bandwidth |
| C. | both voltage gain and bandwidth |
| D. | none of the above |
| Answer» D. none of the above | |
| 444. |
Two identical FETs each having parameters gm and rd are connected is parallel. The composite FET has parameters |
| A. | 0.5 gm and 2 rd |
| B. | 0.5 gm and 0.5 rd |
| C. | 2 gm and 2 rd |
| D. | 2 gm and 0.5 rd |
| Answer» E. | |
| 445. |
Consider 49 cascaded amplifiers having individual rise time as 2 n sec. 3 n sec. ... 50 n sec. The input waveform rise time is 1 n sec. Then the output signal rise time is given time by (Assume output signal rise time is measured within 10 percent range of the final output signal.) |
| A. | 39 - 28 μsec |
| B. | 2.28 μsec |
| C. | 0.228 μsec |
| D. | 39.28 μsec |
| Answer» D. 39.28 Œºsec | |
| 446. |
The feedback technique employed in the following circuit is |
| A. | voltage series feedback |
| B. | current series feedback |
| C. | voltage shunt feedback |
| D. | current shunt feedback |
| Answer» D. current shunt feedback | |
| 447. |
If re is ac resistance of diode, the Thevenin input impedance of a differential amplifier is |
| A. | re |
| B. | bre |
| C. | 2 bre |
| D. | 0.5 bre |
| Answer» D. 0.5 bre | |
| 448. |
The input resistance R, of an ideal voltage amplifier is __________ and that of a current amplifier is __________ . |
| A. | zero, zero |
| B. | infinite, infinite |
| C. | zero, infinite |
| D. | infinite, zero |
| Answer» E. | |
| 449. |
JFET has __________ degree of isolation between input and output, and a __________ noise figure. |
| A. | low, low |
| B. | high, high |
| C. | low, high |
| D. | high, low |
| Answer» E. | |
| 450. |
Generally op amp is used in |
| A. | cascaded loop |
| B. | either (a) or (c) |
| C. | a virtual ground at input |
| D. | a virtual ground at output |
| Answer» C. a virtual ground at input | |