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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.
| 651. |
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 voltage multiplication is |
| A. | 25 |
| B. | 50 |
| C. | 125 |
| D. | 250 |
| Answer» E. | |
| 652. |
A diode can have a very high forward resistance. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 653. |
Which of the following statement about JFET is correct? |
| A. | In an N-channel JFET, the channel is the narrowest under zero gate bias condition |
| B. | In a JFET the gates are always forward biased |
| C. | In a JFET, gate-source cut off voltage is numerically equal to the pinch off voltage |
| D. | It is a voltage controlled device |
| Answer» D. It is a voltage controlled device | |
| 654. |
The multivibrator circuit that has a typical application of converting sinusoidal input into a square wave output is |
| A. | emitter coupled binary |
| B. | Schmitt trigger |
| C. | monoshot multivibrator |
| D. | free-running multivibrator |
| Answer» C. monoshot multivibrator | |
| 655. |
Quartz crystal has |
| A. | very small Q |
| B. | small Q |
| C. | very high Q |
| D. | Q less than 1 |
| Answer» D. Q less than 1 | |
| 656. |
In figure VBE = 0.7 V. If base current required to saturate the transistor is 0.1 mA, Vi = |
| A. | 5 V |
| B. | 5.7 V |
| C. | 10 V |
| D. | 10.7 V |
| Answer» C. 10 V | |
| 657. |
Which of the following is necessary transistor action? |
| A. | The base region must be very wide |
| B. | The base region must be very narrow |
| C. | The base region must be made of some insulating material |
| D. | The collector region must be heavily doped |
| Answer» C. The base region must be made of some insulating material | |
| 658. |
The transistor of following figure in Si diode with a base current of 40 μA and ICBO = 0, if VBB = 6V, RE = 2 kΩ and β = 90, IBQ = 20 μA then IEQ = |
| A. | 1800 μA |
| B. | 180 μA |
| C. | 2000 μA |
| D. | 3000 μA |
| Answer» B. 180 ŒºA | |
| 659. |
In a CE amplifier the ac cut off voltage is 9 V and slope of ac load line is - 0.5 mA/V. The ac saturation current is |
| A. | 9 mA |
| B. | 4.5 mA |
| C. | 3 mA |
| D. | 18 mA |
| Answer» C. 3 mA | |
| 660. |
An inverting amplifier has R1 = 10 kΩ, and Rf = 150 kΩ then the O/P voltage, if input voltage Vi = 1 volt. |
| A. | -15 V |
| B. | -10 V |
| C. | 15 V |
| D. | -14 V |
| Answer» B. -10 V | |
| 661. |
In CE amplifier circuit, voltage gain is directly proportional to |
| A. | β |
| B. | collector supply voltage |
| C. | base resistance |
| D. | none of the above |
| Answer» B. collector supply voltage | |
| 662. |
A voltage doubler circuit is fed by a voltage Vm sin ωt. The output voltage will be nearly 2 Vm only if |
| A. | load resistance is small |
| B. | load resistance is large |
| C. | load resistance is neither small nor large |
| D. | either (a) or (c) |
| Answer» C. load resistance is neither small nor large | |
| 663. |
As compared to a full wave diode rectifier circuit using centre tapped transformer, the bridge diode rectifier circuit has the main advantage of |
| A. | higher current carrying capacity |
| B. | higher efficiency |
| C. | lower ripple factor |
| D. | lower PIV |
| Answer» E. | |
| 664. |
The main application of enhancement mode MOSFET is in |
| A. | amplifier circuits |
| B. | oscillator circuits |
| C. | switching circuits |
| D. | all of the above |
| Answer» D. all of the above | |
| 665. |
In operational Amplifier, Common mode voltage gain should be |
| A. | 0 |
| B. | ‚àû |
| C. | 1 |
| D. | 0.5 |
| Answer» B. ‚àû | |
| 666. |
Assertion (A): In an op-amp the voltage gain and band width can be adjusted as per requirementReason (R): Large value capacitor can also be fabricated on a chip |
| 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 | |
| 667. |
In most transistor the collector region is made physically larger than the emitter region |
| A. | for dissipating heat |
| B. | to distinguish it from other regions |
| C. | as it is sensitive to ultraviolet rays |
| D. | to reduce resistance in the path of flow of electrons |
| Answer» B. to distinguish it from other regions | |
| 668. |
In a class C operation VCC = 40 V and VCE(sat) = 0.4 V. The efficiency is |
| A. | 0.9 |
| B. | 0.495 |
| C. | 0.01 |
| D. | 0.005 |
| Answer» B. 0.495 | |
| 669. |
In a CE amplifier the ac emitter resistance |
| A. | is zero |
| B. | is high |
| C. | is very high |
| D. | may have any value |
| Answer» B. is high | |
| 670. |
The A.C. resistance of the emitter diode will be |
| A. | 5.05 Ω |
| B. | 50.5 Ω |
| C. | 505 Ω |
| D. | 5050 Ω |
| Answer» C. 505 Œ© | |
| 671. |
Which of the following amplifier circuit using junction transistor has the best gain? |
| A. | Common base |
| B. | Common emitter |
| C. | Common collector |
| D. | All have the same gain |
| Answer» C. Common collector | |
| 672. |
Two CE stages, 1 and 2 are coupled through a capacitor. VCC is the same for both. Base resistances RB1 and RB2 are such that RB1 > RB2. Then |
| A. | base currents for both stages are equal |
| B. | base current of stage 1 is more than that of stage 2 |
| C. | base current of stage 2 is more than that of stage 1 |
| D. | either (b) or (c) |
| Answer» D. either (b) or (c) | |
| 673. |
A class A transformer coupled power amplifier is to deliver 10 W output. The power rating of transistor should not be less than |
| A. | 5 W |
| B. | 10 W |
| C. | 20 W |
| D. | 40 W |
| Answer» D. 40 W | |
| 674. |
Assertion (A): A class C amplifier can also be used as frequency multiplierReason (R): When narrow current pulses drive a resonant circuit the output can be a near perfect sine wave |
| 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 | |
| 675. |
In a single-stage RC coupled common emitter amplifier, the phase shift at the lower 3 dB frequency is |
| A. | zero |
| B. | 135° |
| C. | 180° |
| D. | 225° |
| Answer» C. 180¬∞ | |
| 676. |
A class C amplifier uses |
| A. | high Q tuned circuit |
| B. | low Q tuned circuit |
| C. | untuned circuit |
| D. | either (b) or (c) |
| Answer» B. low Q tuned circuit | |
| 677. |
Which of the following h parameters is an admittance? |
| A. | hie |
| B. | hre |
| C. | hfe |
| D. | hoe |
| Answer» E. | |
| 678. |
The conversion or collector circuit efficiency is a measure |
| A. | how successfully the active device converts D.C. power to A.C. signal power |
| B. | how much distortion in output is reduced with respect to input |
| C. | how successfully the active device converts A.C. power to D.C. signal power |
| D. | none of the above |
| Answer» B. how much distortion in output is reduced with respect to input | |
| 679. |
The dc load current in a bridge rectifier circuit is 10 mA. The dc load current through each diode is |
| A. | 40 mA |
| B. | 20 mA |
| C. | 10 mA |
| D. | 5 mA |
| Answer» E. | |
| 680. |
In CE amplifier the base current is very high. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 681. |
The early effect in BJT is caused by |
| A. | fast turn on |
| B. | fast turn off |
| C. | large collector base reverse bias |
| D. | large emitter base forward bias |
| Answer» D. large emitter base forward bias | |
| 682. |
Assertion (A): Negative feedback reduces the bandwidth of an amplifier Reason (R): Negative feedback stabilizes the gain of an 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» E. | |
| 683. |
A 1 ms pulse can be stretched to 1 sec pulse by using |
| A. | an astable multivibrator |
| B. | a monostable multivibrator |
| C. | a bistable multivibrator |
| D. | a Schmitt trigger circuit |
| Answer» C. a bistable multivibrator | |
| 684. |
A virtual ground is a ground for |
| A. | voltage |
| B. | current |
| C. | both voltage and current |
| D. | voltage but not for current |
| Answer» E. | |
| 685. |
To draw ac equivalent circuit for a CE amplifier we should |
| A. | Reduce all dc sources to zero |
| B. | Short all capacitors |
| C. | Reduce all dc sources to zero and short all capacitors |
| D. | Reduce all dc sources to zero and open all capacitors |
| Answer» D. Reduce all dc sources to zero and open all capacitors | |
| 686. |
An op-amp has |
| A. | low input and output impedance |
| B. | low input impedance and high output impedance |
| C. | low output impedance and high input impedance |
| D. | high output impedance and high input impedance |
| Answer» D. high output impedance and high input impedance | |
| 687. |
Assertion (A): The main use of Miller integrator is to generate rampReason (R): An inverting amplifier can handle more than one input at the same time. |
| 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 | |
| 688. |
The V MOS can handle __________ currents than a conventional MOSFET. |
| A. | much lower |
| B. | almost same |
| C. | almost half |
| D. | much larger |
| Answer» E. | |
| 689. |
Consider the following statements :The lower cut off frequencies of an RC coupled amplifier depend on input and output coupling capacitoremitter by pass capacitorsjunction capacitances Which of the above are correct? |
| A. | 1 only |
| B. | 2 only |
| C. | 1 and 2 |
| D. | 2 and 3 |
| Answer» B. 2 only | |
| 690. |
Thermal runaway will take place if the quiescent point is such that |
| A. | VCE > |
| B. | VCE < VCC |
| C. | VCE < 2VCC |
| D. | VCE < |
| Answer» B. VCE < VCC | |
| 691. |
The output impedance of an ideal op-amp is |
| A. | zero |
| B. | low |
| C. | high |
| D. | infinite |
| Answer» B. low | |
| 692. |
Which of the following best represents the input impedance of an actual op-amp? |
| A. | 10 ohm |
| B. | 1 k ohm |
| C. | 1 M ohm |
| D. | 100 M ohm |
| Answer» D. 100 M ohm | |
| 693. |
Which distortion is least objectionable in case of audio amplifiers? |
| A. | Phase distortion |
| B. | Frequency distortion |
| C. | Harmonic distortion |
| D. | Inter-modulation distortion |
| Answer» B. Frequency distortion | |
| 694. |
In figure if C is replaced by short circuit then RB will be |
| A. | 425 K |
| B. | 412 K |
| C. | 474 K |
| D. | 400 K |
| Answer» D. 400 K | |
| 695. |
In a CE amplifier the collector resistance is short circuited. The ac output voltage will |
| A. | increases |
| B. | remains the same |
| C. | increases or decreases |
| D. | decreases |
| Answer» E. | |
| 696. |
Which of the following is the common feature between FETs and bipolars? |
| A. | Have low input impedance |
| B. | Have low voltage gain |
| C. | Are difficult to bias |
| D. | None of them |
| Answer» E. | |
| 697. |
In a biased JFET (Figure) the shape of the channel is as shown because |
| A. | it is the property of material used |
| B. | the drain end is more reverse biased than source end |
| C. | drain end is more forward biased than source end |
| D. | impurity profile changes with distance |
| Answer» C. drain end is more forward biased than source end | |
| 698. |
A multivibrator can be used as a |
| A. | cavity resonator |
| B. | harmonic generator |
| C. | wave form modifier |
| D. | any of the above |
| Answer» D. any of the above | |
| 699. |
The parameter h11 for CB circuit is higher than that for CE circuit. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 700. |
A voltage multiplier circuit, using diodes and capacitors is suitable for |
| A. | high voltage high current device |
| B. | high voltage low current device |
| C. | low voltage low current device |
| D. | low voltage high current device |
| Answer» C. low voltage low current device | |