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.
| 551. |
In the following figure C = 0.02 μF, and Vth is known to be of frequency ω = 107 rad/sec and rd = 2.5 Ω and ZTh = RTh = 10 Ω Then phase angle between id and Vd |
| A. | 26.5° |
| B. | 25° |
| C. | 30° |
| D. | 0° |
| Answer» B. 25¬∞ | |
| 552. |
A CE amplifier has a high input signal. In the wave shape of emitter current |
| A. | positive and negative half cycles will be symmetrical |
| B. | positive half cycle will be elongated and negative half cycle will be compressed |
| C. | positive half cycle will be compressed and negative half cycle will be elongated |
| D. | the half cycles may be either elongated or compressed |
| Answer» C. positive half cycle will be compressed and negative half cycle will be elongated | |
| 553. |
FET amplifier is more difficult to analyse than BJT amplifier. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 554. |
The input resistance of FET in the low frequency small signal operation is |
| A. | infinitely high |
| B. | around 1 kΩ |
| C. | around 50 Ω |
| D. | very small |
| Answer» B. around 1 kŒ© | |
| 555. |
The approximate value of input impedance of CE amplifier with emitter resistance RE is given by |
| A. | hie + Ai RE |
| B. | hie + (1 + hfe) RE |
| C. | hie |
| D. | (1 + hfe) RE |
| Answer» D. (1 + hfe) RE | |
| 556. |
Sweep voltage generators, sweep current generators, multivibrators and blocking oscillators can be combined as |
| A. | negative resistance oscillators |
| B. | tuned base tuned collector oscillators |
| C. | relaxation oscillators |
| D. | L-C tuned oscillators |
| Answer» D. L-C tuned oscillators | |
| 557. |
Which of the following is the point of reference JFET? |
| A. | Drain |
| B. | Gate |
| C. | Source |
| D. | None of the above |
| Answer» D. None of the above | |
| 558. |
In a CE amplifier drives a low load resistance directly the result will be |
| A. | overloading of amplifier |
| B. | underloading of amplifier |
| C. | overloading or underloading of amplifier depending on circuit |
| D. | none of the above |
| Answer» B. underloading of amplifier | |
| 559. |
The gate-source voltage that reduces the drain current to approximately zero is called |
| A. | gate-source on voltage |
| B. | gate-source voltage |
| C. | pinch-off voltage |
| D. | gate-source cut-off voltage |
| Answer» D. gate-source cut-off voltage | |
| 560. |
The input to negative clamper has a peak value of Vp. Then in the output the positive and negative peaks are nearly |
| A. | 0 and -2 V respectively |
| B. | Vp and -Vp respectively |
| C. | 2 Vp and 0 respectively |
| D. | none of the above |
| Answer» B. Vp and -Vp respectively | |
| 561. |
In a shunt-shunt negative feedback amplifier, as compared to the basic amplifier |
| A. | both input and output impedances, decrease |
| B. | input impedance decreases but output impedance increase |
| C. | I/P impedance increases but O/P impedance decreases |
| D. | both input and O/P impedance increases |
| Answer» C. I/P impedance increases but O/P impedance decreases | |
| 562. |
Three cascaded stages have gains of 10, 20 and 25. The overall gain will be |
| A. | 10 |
| B. | 55 |
| C. | 500 |
| D. | 5000 |
| Answer» E. | |
| 563. |
In a CE amplifier, the collector resistance is 6 kΩ and load resistance is 3 kΩ. The ac load resistance is |
| A. | 9 kΩ |
| B. | 6 kΩ |
| C. | 3 kΩ |
| D. | 2 kΩ |
| Answer» E. | |
| 564. |
Assertion (A): The ac load line is different from dc load lineReason (R): The ac load resistance seen by collector and emitter is different from dc load resistance |
| 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 | |
| 565. |
If the Q of a single-stage single-tuned amplifier is doubled, then its bandwidth will |
| A. | remain same |
| B. | become half |
| C. | become doubled |
| D. | become four times |
| Answer» C. become doubled | |
| 566. |
Class C amplifier is suitable for |
| A. | a narrow frequency band |
| B. | a wide frequency band |
| C. | audio frequencies |
| D. | either (b) or (c) |
| Answer» B. a wide frequency band | |
| 567. |
In a CE transistor amplifier, when collector-emitter voltage increases |
| A. | the instantaneous operating point moves up the load line |
| B. | the instantaneous operating point moves down the line |
| C. | load current increases |
| D. | none of the above |
| Answer» B. the instantaneous operating point moves down the line | |
| 568. |
If a transistor is operating with both of its Junctions forward biased, but with the collector base forward biased, but with the collector base forward bias greater than the emitter-base forward bias, then it is operating in the |
| A. | forward active mode |
| B. | reverse saturation mode |
| C. | reverse active mode |
| D. | forward saturation mode |
| Answer» D. forward saturation mode | |
| 569. |
Low frequency response of amplifier is mainly limited by |
| A. | input capacitor |
| B. | bypass capacitor |
| C. | output capacitor |
| D. | biasing capacitor |
| Answer» C. output capacitor | |
| 570. |
A potential of 7 V is applied to a silicon diode. A resistance of 1 kΩ is also connected in series. If the diode is forward biased, the current in the circuit is |
| A. | 7 mA |
| B. | 6.3 mA |
| C. | 0.7 mA |
| D. | 0 |
| Answer» C. 0.7 mA | |
| 571. |
In a rectifier only a portion of input power is converted into DC power. The rest is AC power. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 572. |
The MOSFET is almost ideal as a switching device because |
| A. | it has linear characteristics |
| B. | it works progressively |
| C. | it consumes low power |
| D. | it has longer life |
| Answer» D. it has longer life | |
| 573. |
A three-section RC phase shift oscillator has R = 10K ohms and C = 0.001 μF. The frequency of oscillations is |
| A. | 1.1 kHz |
| B. | 2.5 kHz |
| C. | 3.3 kHz |
| D. | 6.5 kHz |
| Answer» E. | |
| 574. |
For a transistor the normal collector voltage is 12 V. If actually it is found to be + 28 V, the trouble could be |
| A. | RL is open |
| B. | RE is open |
| C. | CE is shorted |
| D. | CE is open |
| Answer» C. CE is shorted | |
| 575. |
Assertion (A): An op-amp amplifier can amplify dc signalReason (R): An op-amp amplifier is a direct coupled amplifier |
| 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 | |
| 576. |
A second-order band-pass active filter can be obtained by cascading a low pass second order section having cut off frequency fOH with a high pass second order section having cut-off frequency fOL provided |
| A. | fOH > fOL |
| B. | fOH < fOL |
| C. | fOH = fOL |
| D. | fOH ≤ 1/2fOL |
| Answer» B. fOH < fOL | |
| 577. |
Which of the following oscillator circuits uses three capacitors in the phase shifting network? |
| A. | Hartley |
| B. | Clapp |
| C. | Colpitt's |
| D. | Both (b) and (c) |
| Answer» C. Colpitt's | |
| 578. |
The derating factor, for ambient temperature higher than specified, for a transistor is about |
| A. | 2.5 mW/°C |
| B. | 0.5 mW/°C |
| C. | 10 mW/°C |
| D. | 20 mW/°C |
| Answer» B. 0.5 mW/¬∞C | |
| 579. |
For a good voltage amplifier, its input impedance should be |
| A. | low as compared to the resistance of the source |
| B. | high as compared to the resistance of the source |
| C. | always inductive |
| D. | always capacitive |
| Answer» C. always inductive | |
| 580. |
For an npn transistor connected as shown in the figure VBE = 0.7 volts. Given that reverse saturation current of the junction at room temperature 300K is 10-13A, the emitter current. |
| A. | 30 mA |
| B. | 39 mA |
| C. | 49 mA |
| D. | 20 mA |
| Answer» D. 20 mA | |
| 581. |
A sine wave is passed through an amplifier which severely limits it symmetrically. If then passes to a second amplifier which is narrow band and tuned to the frequency of the original sine wave. What will be the output wave from this second amplifier? |
| A. | A square wave of the same frequency as that of the original sine wave |
| B. | A square wave of double the frequency of that of original sine wave |
| C. | A sine wave of constant amplitude at the frequency of the original sine wave |
| D. | A sine wave of constant amplitude at double frequency of the original sine wave |
| Answer» D. A sine wave of constant amplitude at double frequency of the original sine wave | |
| 582. |
Which one of the following is connect expression of id for figure? |
| A. | |
| B. | |
| Answer» B. | |
| 583. |
When a 1 V increase in gate voltage changes the drain current 10 mA in an FET, its gm equals |
| A. | 10 μμ |
| B. | 100 μμ |
| C. | 1000 μμ |
| D. | 10000 μμ |
| Answer» E. | |
| 584. |
In the circuit of figure, v0 = |
| A. | 3 v1 + 4 v2 |
| B. | -3 v1 - 4 v2 |
| C. | 4 v1 + 3 v2 |
| D. | -4 v1 - 3 v2 |
| Answer» C. 4 v1 + 3 v2 | |
| 585. |
In a CE class A amplifier the quiescent current and voltage are ICQ and VCEQ. The maximum power output can be |
| A. | (VCEQ)(ICQ) |
| B. | |
| Answer» C. | |
| 586. |
A cascade amplifier will have higher cut off frequency |
| A. | equal to that of single stage amplifier |
| B. | less than that of single stage amplifier |
| C. | more than that of single stage amplifier |
| D. | none of these |
| Answer» C. more than that of single stage amplifier | |
| 587. |
The advantage of FET over BJT is |
| A. | high input impedance |
| B. | lower noise |
| C. | no thermal runaway |
| D. | all of the above |
| Answer» E. | |
| 588. |
A transistor with a = 0.9 and ICBO = 10 μA is biased so that IBQ = 90 μA. Then IEQ will be |
| A. | 5.15 mA |
| B. | 5.2 mA |
| C. | 5 mA |
| D. | 990 mA |
| Answer» E. | |
| 589. |
According to Barkhausen criteria in order to sustain the oscillations |
| A. | loop gain of the circuit must be negligible |
| B. | loop gain of the circuit must be equal to unity |
| C. | the phase shift around the circuit must be 180° |
| D. | none of the above |
| Answer» D. none of the above | |
| 590. |
The disadvantage of transformer coupling in amplifier is |
| A. | cost of transformer at audio frequencies |
| B. | size of transformer at audio frequencies |
| C. | size of transformer at radio frequencies |
| D. | cost and size of transformer at audio frequencies |
| Answer» E. | |
| 591. |
Most small signal transistors are |
| A. | N-P-N, silicon, in a plastic package |
| B. | P-N-P, silicon, in a plastic package |
| C. | N-P-N, germanium in a metallic case |
| D. | P-N-P, germanium in a metallic case |
| Answer» B. P-N-P, silicon, in a plastic package | |
| 592. |
For holding the drain current constant in spite of large changes in JFET parameters |
| A. | current source bias is used |
| B. | voltage divider bias is used |
| C. | reverse bias is used |
| D. | no bias is used |
| Answer» B. voltage divider bias is used | |
| 593. |
Which amplifier has the higher power gain? |
| A. | Common emitter |
| B. | Common collector |
| C. | Common base |
| D. | Both CC and CE |
| Answer» B. Common collector | |
| 594. |
Figure shows small signal model of CB amplifier circuit. Then I and R are respectively equal to |
| A. | a ie and re |
| B. | |
| C. | a ie and re (a - 1) |
| Answer» B. | |
| 595. |
In a class C operation VCC = 30 V and VCE(sat) = 2 V. The efficiency is |
| A. | 0.9375 |
| B. | 0.88 |
| C. | 0.0666 |
| D. | 0.0333 |
| Answer» B. 0.88 | |
| 596. |
The units of are |
| A. | V |
| B. | V-1 |
| C. | J |
| D. | J/K |
| Answer» C. J | |
| 597. |
A full wave diode rectifier using centre tapped transformer has diodes with forward resistance of 50 ohms each. The load resistance of 50 ohms each. The load resistance is also 50 ohms. The voltage regulation is |
| A. | 0.2 |
| B. | 0.5 |
| C. | 1 |
| D. | 2 |
| Answer» D. 2 | |
| 598. |
The input gate current of a FET is |
| A. | a few amperes |
| B. | a few milli amperes |
| C. | a few micro amperes |
| D. | negligible |
| Answer» E. | |
| 599. |
In an RC phase shift oscillator, the total phase shift of the three RC lead networks is |
| A. | 360° |
| B. | 180° |
| C. | 90° |
| D. | 0° |
| Answer» C. 90¬∞ | |
| 600. |
In the circuit of figure β = 100 and quiescent value of base current is 20 μA. The quiescent value of collector current is |
| A. | 0.2 μA |
| B. | 2 μA |
| C. | 2 mA |
| D. | 20 mA |
| Answer» D. 20 mA | |