MCQOPTIONS
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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.
| 451. |
High frequency oscillations can be caused by |
| A. | electric coupling |
| B. | magnetic coupling |
| C. | ground loop |
| D. | all of the above |
| Answer» E. | |
| 452. |
For a BJT if β = 50, ICEO = 3 μA and IC = 1.2 mA then IE |
| A. | 1 mA |
| B. | 1.2 mA |
| C. | 1.3 mA |
| D. | 1.4 mA |
| Answer» C. 1.3 mA | |
| 453. |
Assertion (A): An ac amplifier uses coupling capacitors at input and outputReason (R): The capacitive reactance varies inversely with frequency. It is infinite for dc |
| 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» B. Both A and R are correct but R is not correct explanation for A | |
| 454. |
A transistor amplifier with 85% efficiency is expected to be |
| A. | class A |
| B. | class B |
| C. | class C |
| D. | class AB |
| Answer» D. class AB | |
| 455. |
Which circuit is called swamped amplifier? |
| A. | CC |
| B. | CE |
| C. | CB |
| D. | Both (a) and (b) |
| Answer» B. CE | |
| 456. |
It has been found that in a rectifier circuit with RC filter one RC section reduces ripple by 15%. Two RC sections are used in cascade the reduction in ripple would be |
| A. | 0.15 |
| B. | 0.3 |
| C. | 1.5 |
| D. | 2.25 |
| Answer» E. | |
| 457. |
Turn off time of a transistor switch is equal to (where ts is storage time and tf is fall time.) |
| A. | ts + tf |
| B. | ts - tf |
| C. | 2ts |
| D. | 2tf |
| Answer» B. ts - tf | |
| 458. |
Assertion (A): In a differential amplifier the current through common emitter resistor is called tail currentReason (R): CMRR of an op-amp indicates how a differential signal amplified |
| 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 | |
| 459. |
The RC network of wein bridge oscillator consists of resistors and capacitors of values R = 220 kΩ and C = 250 PF Determine the frequency of oscillation |
| A. | 2.98 kHz |
| B. | 3 kHz |
| C. | 2 kHz |
| D. | 10 kHz |
| Answer» B. 3 kHz | |
| 460. |
A non-inverting voltage feedback amplifier is a |
| A. | voltage amplifier |
| B. | current amplifier |
| C. | current to voltage converter |
| D. | voltage to current converter |
| Answer» B. current amplifier | |
| 461. |
Figure shows basic Hartley oscillator configuration. Do you think the polarities marked for the split coiled are correct? |
| A. | yes they are |
| B. | no they are not |
| C. | it really doesn't matter |
| D. | none of the above |
| Answer» C. it really doesn't matter | |
| 462. |
If the op-amp in figure has a unity gain frequency of 1 MHz, the cut off frequency is |
| A. | 100 kHz |
| B. | 1 MHz |
| C. | 10 MHz |
| D. | 90 MHz |
| Answer» B. 1 MHz | |
| 463. |
The properties of JFET resemble those of |
| A. | thermionic values |
| B. | N-P-N transistors |
| C. | P-N-P transistors |
| D. | unijunction transistor |
| Answer» C. P-N-P transistors | |
| 464. |
In figure vi = 10 mV dc maximum. The maximum possible dc output offset voltage is |
| A. | 60 mV dc |
| B. | 110 mV dc |
| C. | 130 mV dc |
| D. | 150 mV dc |
| Answer» C. 130 mV dc | |
| 465. |
In figure we need an ac ground. The proper value of C is |
| A. | 1000 μF |
| B. | 100 μF |
| C. | 10 μF |
| D. | 1 μF |
| Answer» B. 100 ŒºF | |
| 466. |
In a commercially available good power supply the voltage regulation is about |
| A. | 0.01 |
| B. | 0.05 |
| C. | 0.1 |
| D. | 0.2 |
| Answer» B. 0.05 | |
| 467. |
Class C operation finds application in |
| A. | RF power amplifiers |
| B. | frequency multipliers |
| C. | both (a) and (b) |
| D. | neither (a) nor (b) |
| Answer» D. neither (a) nor (b) | |
| 468. |
Assertion (A): In an op-amp the gain bandwidth product equals ffinityReason (R): The change in open loop gain of an amplifier has almost no effect on closed loop gain |
| 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 | |
| 469. |
Which coupling produces the minimum interference with frequency response? |
| A. | RC coupling |
| B. | Transformer coupling |
| C. | Direct coupling |
| D. | Impedance coupling |
| Answer» D. Impedance coupling | |
| 470. |
Assertion (A): The circuit in figure produces repetitive narrow pulses when input is fed with sine or triangular waveform having peak value more than + VReason (R): The high gain op-amp produces voltages at two levels. If input is more than + V, the output is + 15 V otherwise the output is - 15 V. |
| A. | A is correct R is wrong |
| B. | A is wrong R is correct |
| C. | overloading of amplifier |
| D. | underloading of amplifier |
| Answer» B. A is wrong R is correct | |
| 471. |
Assertion (A): If power gain doubles the power gain increases by 3 dBReason (R): The bel power gain of cascaded stages is equal to sum of each bel power gain |
| 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» B. Both A and R are correct but R is not correct explanation for A | |
| 472. |
RC oscillator can be used upto |
| A. | 50 kHz |
| B. | 100 kHz |
| C. | active region |
| D. | saturation region |
| Answer» C. active region | |
| 473. |
For an op-amp source follower circuit |
| A. | input and output voltages have same magnitude |
| B. | output and input voltages are in phase |
| C. | output and input voltages are in phase but have different magnitudes |
| D. | output and input voltages have same magnitude and are in phase |
| Answer» D. output and input voltages have same magnitude and are in phase | |
| 474. |
Figure shows a zener circuit and characteristic of the zener used. If R2 is the lowest load resistance, then for proper voltage regulation R1 must be |
| A. | more than |
| B. | more than |
| C. | less than |
| D. | less than |
| Answer» D. less than | |
| 475. |
Class-B amplifier has less efficiency compared to |
| A. | class A |
| B. | class B |
| C. | class C |
| D. | class A, AB and C |
| Answer» B. class B | |
| 476. |
In a class C power amplifier the input frequency of ac signal is 1 MHz. If tank circuit has C = 1000 pF, the value of L = |
| A. | 25 μH |
| B. | 50 μH |
| C. | 100 μH |
| D. | 200 μH |
| Answer» B. 50 ŒºH | |
| 477. |
If the changes in zener current in a voltage regulator circuit are too large, it can be corrected by using a |
| A. | emitter follower |
| B. | CE amplifier |
| C. | capacitor |
| D. | either (a) or (b) |
| Answer» B. CE amplifier | |
| 478. |
When the ac input signal is very large the instantaneous operating point CE amplifier moves all the way between |
| A. | ac saturation and ac cut off points |
| B. | ac operating and ac cut off points |
| C. | ac saturation and ac operating points |
| D. | none of the above |
| Answer» B. ac operating and ac cut off points | |
| 479. |
In a BJT amplifier the power gain from base to collector is 4000. The power gain in dB is |
| A. | 3.6 |
| B. | 36 |
| C. | 7.2 |
| D. | 72 |
| Answer» C. 7.2 | |
| 480. |
In figure the dc emitter current of each transistor is about |
| A. | 4 mA |
| B. | 2 mA |
| C. | 3 mA |
| D. | 1 mA |
| Answer» E. | |
| 481. |
One input terminal of high gain comparator circuit is connected to ground and a sinusoidal voltage is applied to the other input. The output of comparator will be |
| A. | half rectified sinusoidal |
| B. | square wave |
| C. | semi-conductor diode |
| D. | P-N-P transistor |
| Answer» E. | |
| 482. |
A transistor amplifier has poles ats1 = - 0.000245 x 109 rad/sec.s2 = - 0.0748 x 109 rad/sec.s3 = - 0.670 x 109 rad/sec.s4 = - 4.38 x 109 rad/sec.The upper 3 dB frequency of the amplifier will be |
| A. | s1 + s4 |
| B. | s4 |
| C. | figure A |
| D. | figure B |
| Answer» B. s4 | |
| 483. |
The transistor specification number 2N refers to |
| A. | triac |
| B. | diac |
| C. | junction transistor |
| D. | FET with one gate |
| Answer» D. FET with one gate | |
| 484. |
In a voltage regulated power supply the zener operates in the breakdown region when (Vin is input voltage and Vz is zener breakdown voltage) |
| A. | Vin < Vz |
| B. | Vin > Vz |
| C. | Vin = Vz |
| D. | both (a) or (b) |
| Answer» C. Vin = Vz | |
| 485. |
Assertion (A): A tuned amplifier uses a parallel tuned circuitReason (R): A tuned amplifier is used to amplify a narrowband frequencies |
| 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» B. Both A and R are correct but R is not correct explanation for A | |
| 486. |
A Hartley oscillator is used for generation |
| A. | very low frequency oscillation |
| B. | radio frequency oscillation |
| C. | microwave oscillation |
| D. | audio-frequency oscillation |
| Answer» E. | |
| 487. |
A feedback network to be used with an amplifier to provide oscillation is tested and found to give an output of 0.124 V with a 0.5 V input. What will be the effect on output if the amplifier's gain is twice that required by the Barkhausen criterion? |
| A. | Linear oscillations |
| B. | Non-linear oscillations |
| C. | Damped oscillations |
| D. | No oscillations |
| Answer» E. | |
| 488. |
An inverting voltage feedback is a |
| A. | voltage amplifier |
| B. | current amplifier |
| C. | current to voltage converter |
| D. | voltage to current converter |
| Answer» D. voltage to current converter | |
| 489. |
For an amplifier, the coupling method which gives the highest gain in |
| A. | impedance coupling |
| B. | transformer coupling |
| C. | capacitance coupling |
| D. | resistance coupling |
| Answer» C. capacitance coupling | |
| 490. |
Common emitter transistor has |
| A. | high current and high voltage gain |
| B. | low current gain and low voltage gain |
| C. | high current gain and low voltage gain |
| D. | low current and voltage gain |
| Answer» B. low current gain and low voltage gain | |
| 491. |
If a = 0.995, IE = 10 mA, ICO = 0.5 mA, then ICEO will be |
| A. | 100 μA |
| B. | 25 μA |
| C. | 10.1 μA |
| D. | 10.5 μA |
| Answer» B. 25 ŒºA | |
| 492. |
A generator with an internal resistance of 600 Ω drives an amplifier whose input resistance is 400 Ω. The generator's open circuit voltages is 1 mV; the amplifier develops 100mV across an 8kΩ load. The current amplification is |
| A. | 2.5 |
| B. | 12.5 |
| C. | 25 |
| D. | 125 |
| Answer» C. 25 | |
| 493. |
A differential amplifier consists of two CB amplifiers. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 494. |
In figure, D2 turns on when |
| A. | vi is more positive than V1 |
| B. | vi is less positive than V1 |
| C. | vi is more negative than V2 |
| D. | vi is less negative than V2 |
| Answer» D. vi is less negative than V2 | |
| 495. |
Which of the following statement about JFET is true? |
| A. | In a JFET, gate and source have opposite polarity with respect to drain irrespective of the type of FET |
| B. | In its schematic symbol for JFET, the arrow always points to p-type material |
| C. | In an n-channel JFET, the channel is the narrowest under zero gate bias condition |
| D. | In JFET, gate source cut off voltage is numerically equal to the pinch off voltage |
| Answer» E. | |
| 496. |
In figure V0 = |
| A. | 11 Vi |
| B. | 10 Vi |
| C. | Vi |
| D. | 0 |
| Answer» D. 0 | |
| 497. |
Assertion (A): A large negative feedback is deliberately introduced in an amplifier to make its gain independent of variation is in parameters of active device and other components.Reason (R): A large negative feedback results in a high value of return difference compared to unity which makes the feedback gain inversely proportional to feedback factor. |
| 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» B. Both A and R are correct but R is not correct explanation for A | |
| 498. |
A transconductance amplifier has |
| A. | high input impedance and low output impedance |
| B. | low input impedance and high output impedance |
| C. | high input and output impedance |
| D. | low input and output impedance |
| Answer» D. low input and output impedance | |
| 499. |
N-channel FETs are superior to p-channel FETs because |
| A. | mobility of electrons is smaller than that of holes |
| B. | mobility of electrons is greater than that of holes |
| C. | they consume less power |
| D. | they have high switching time |
| Answer» C. they consume less power | |
| 500. |
One of the following can be used to generate a pulse whenever triggered |
| A. | flip-flop |
| B. | monostable multivibrator |
| C. | stable multivibrator |
| D. | Schmitt trigger |
| Answer» C. stable multivibrator | |