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.
| 701. |
A FET |
| A. | has two P-N junctions |
| B. | has three P-N junctions |
| C. | depends on the variation of the depletion layer width with reverse voltage, for its operation |
| D. | depends on the variation of a magnetic field for its operation |
| Answer» C. depends on the variation of the depletion layer width with reverse voltage, for its operation | |
| 702. |
In a transistor IE = 10 mA, ICO = 0.5 μA and a = 0.995. Then ICEO = |
| A. | 100 μA |
| B. | 25 μA |
| C. | 10.1 mA |
| D. | 10.5 mA |
| Answer» B. 25 ŒºA | |
| 703. |
Ultra high frequency oscillators work in the range |
| A. | 20 Hz to 20 kHz |
| B. | 1 kHz to 30 kHz |
| C. | 30 kHz to 30 MHz |
| D. | above 30 MHz |
| Answer» E. | |
| 704. |
In which configuration does output ac voltage appear between emitter and ground? |
| A. | CE |
| B. | CB |
| C. | CC |
| D. | Both CE and CB |
| Answer» D. Both CE and CB | |
| 705. |
Assertion (A): The gain of an FET amplifier can be changed by changing gmReason (R): Most receivers use automatic gain control to counteract changes in volume caused by fading |
| 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 | |
| 706. |
RC network shown in the given figure can provide a maximum theoretical phase shift of |
| A. | 90° |
| B. | 180° |
| C. | 270° |
| D. | 360° |
| Answer» C. 270¬∞ | |
| 707. |
The emitter coupled pair of BJT's gives a linear transfer relation between the differential output voltage and the differential input voltage Vid only when the magnitude of Vid is less a times the thermal voltage, where a is |
| A. | 4 |
| B. | 3 |
| C. | 2 |
| D. | 1 |
| Answer» E. | |
| 708. |
In an amplifier circuit the emitter is at ac ground potential in a |
| A. | CB circuit |
| B. | CC circuit |
| C. | CE circuit |
| D. | both CB and CE circuit |
| Answer» D. both CB and CE circuit | |
| 709. |
In a full wave rectifier circuit using centre tapped transformer, the peak voltage across half the secondary winding is 40 V. If diodes are ideal, the average output voltage is |
| A. | 40 V |
| B. | 25.5 V |
| C. | 20 V |
| D. | 2.55 V |
| Answer» C. 20 V | |
| 710. |
A sine wave with slew rate distortion looks like |
| A. | step wave |
| B. | square wave |
| C. | triangular wave |
| D. | cosine wave |
| Answer» D. cosine wave | |
| 711. |
Gain stability in an oscillator can bs achieved by |
| A. | providing negative feedback |
| B. | providing positive feedback |
| C. | using low Q circuits |
| D. | controlling the gain |
| Answer» E. | |
| 712. |
In oscillators class C operation is preferred because |
| A. | is most efficient |
| B. | has frequency stability |
| C. | gives larger output |
| D. | it produces nearly square waves |
| Answer» E. | |
| 713. |
In a P-N-P junction transistor as compared to base region is more heavily doped so that |
| A. | leakage current is minimized |
| B. | recombination will be increased in the base region |
| C. | the flow across the base regional is only because of electrons |
| D. | the flow across the base region is mainly because of holes |
| Answer» E. | |
| 714. |
In a CE amplifier the dc load line is the same as ac load line when |
| A. | ac collector resistance and dc collector resistance are equal |
| B. | ac collector resistance and dc emitter resistance are equal |
| C. | ac collector resistance is very high |
| D. | ac collector resistance is one half of dc collector resistance |
| Answer» D. ac collector resistance is one half of dc collector resistance | |
| 715. |
Assertion (A): The horizontal intercept of dc load line is the same as ideal cut off pointReason (R): When a transistor is in cut off region, collector current is zero |
| 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 | |
| 716. |
In a current mirror |
| A. | the i - v curve of compensating diode is similar to collector curve of transistor |
| B. | the i - v curve of compensating diode is similar to transconductance curve of transistor |
| C. | either (a) or (b) |
| D. | neither (a) nor (b) |
| Answer» C. either (a) or (b) | |
| 717. |
Which mode is usually preferred for cascading? |
| A. | CE |
| B. | CB |
| C. | CC |
| D. | Any of the above |
| Answer» B. CB | |
| 718. |
A boot strap generally incorporates |
| A. | CB configuration |
| B. | CE configuration |
| C. | emitter follower |
| D. | none of the above |
| Answer» B. CE configuration | |
| 719. |
The element in the feedback circuit of a logarithmic amplifier using op-amp is |
| A. | a resistor |
| B. | a capacitor |
| C. | an inductor |
| D. | a diode |
| Answer» E. | |
| 720. |
The ripple factor of a full wave rectifier is about 0.5. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 721. |
In figure the input and output Miller capacitances are |
| A. | 0.25 μF each |
| B. | 500 pF each |
| C. | 0.25 μF and 500 pF respectively |
| D. | 500 pF and 0.25 μF respectively |
| Answer» B. 500 pF each | |
| 722. |
The main use of JFET with a |
| A. | frequency mixer |
| B. | source follower |
| C. | voltage doubler |
| D. | trigger |
| Answer» C. voltage doubler | |
| 723. |
In every practical oscillator the loop gain is slightly more than unit and amplitude of oscillations is limited by |
| A. | magnitude of loop gain |
| B. | onset of non-linearity |
| C. | magnitude of gain |
| D. | β |
| Answer» C. magnitude of gain | |
| 724. |
Assertion (A): Direct coupled amplifiers are rarely usedReason (R): Direct coupled amplifiers suffer from the disadvantage of drift |
| 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 | |
| 725. |
Which one of the following devices is not used as the controller in a stabilizer? |
| A. | DIAC |
| B. | TRIAC |
| C. | SCR |
| D. | Power transistor |
| Answer» B. TRIAC | |
| 726. |
Most of the transistor data sheets specify the power rating for an ambient temperature of |
| A. | 10°C |
| B. | 25°C |
| C. | 50°C |
| D. | 75°C |
| Answer» C. 50¬∞C | |
| 727. |
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 power gain is |
| A. | 125 |
| B. | 250 |
| C. | 1125 |
| D. | 3125 |
| Answer» E. | |
| 728. |
The input resistance Ri of the amplifier shown in the figure |
| A. | |
| B. | 100 kΩ |
| C. | 40 kΩ |
| Answer» C. 40 kŒ© | |
| 729. |
In an amplifier if conductor during the cycle is from 0 to 90° and again from 180° to 270°, the amplifier will be termed as |
| A. | class A |
| B. | class B |
| C. | class C |
| D. | class AB |
| Answer» C. class C | |
| 730. |
A Colpitt's oscillator uses |
| A. | a tapped inductor |
| B. | an inductor and two capacitors |
| C. | both (a) and (b) |
| D. | either (a) or (b) |
| Answer» D. either (a) or (b) | |
| 731. |
It is desired to reduce distortion in an amplifier from 8% to 2% by using 5% negative feedback. The open and closed loop gains respectively are |
| A. | 60 and 15 |
| B. | 15 and 60 |
| C. | 6 and 1.5 |
| D. | 1.5 and 6 |
| Answer» B. 15 and 60 | |
| 732. |
JFET is also known as |
| A. | linear device |
| B. | square law device |
| C. | inverse law device |
| D. | logarithmic law device |
| Answer» C. inverse law device | |
| 733. |
A P-channel MOSFET operating in the enhancement mode is characterized by Vt = - 4 V and IDQ = - 10 mA, when VGSQ = - 5.5 V, what will be VGSQ if IDQ = -15 mA and ID, on = - 16 mA |
| A. | - 2 V |
| B. | 3 V |
| C. | 0.13 V |
| D. | 1.3 V |
| Answer» D. 1.3 V | |
| 734. |
A Hartley oscillator is used for |
| A. | very low frequencies |
| B. | radio frequencies |
| C. | micro wave frequencies |
| D. | audio frequency |
| Answer» C. micro wave frequencies | |
| 735. |
Assertion (A): A class C amplifier is a timed amplifier which needs a tank circuit as the load in the collector circuit of the transistor for its proper operationReason (R): In class C operation collector current flows for less than 180° of the ac cycle and thus flows in pulses |
| 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 | |
| 736. |
In an LC filter, the ripple factor, |
| A. | increases with load current |
| B. | increases with load resistance |
| C. | remains constant with the load current |
| D. | has the lowest value |
| Answer» E. | |
| 737. |
In which of the following circuits is op-amp used in open loop configuration? |
| A. | Comparator |
| B. | Summing amplifier |
| C. | Integrating amplifier |
| D. | Logarithmic amplifier |
| Answer» B. Summing amplifier | |
| 738. |
Output of a phase splitter is |
| A. | a pair of sine waves of unequal amplitude |
| B. | a pair of sine waves of equal amplitudes |
| C. | a pair of sine waves of equal amplitudes and opposite phase |
| D. | a pair of sine waves of unequal amplitudes and opposite phase |
| Answer» D. a pair of sine waves of unequal amplitudes and opposite phase | |
| 739. |
Which amplifier will be preferred for highest gain? |
| A. | Darlington's pair |
| B. | Single stage amplifier |
| C. | Cascade amplifier |
| D. | Depends on the circuitry |
| Answer» D. Depends on the circuitry | |
| 740. |
As compared to a BJT amplifier circuit, a JFET amplifier circuit |
| A. | has low input impedance |
| B. | has high input impedance |
| C. | has very low input impedance |
| D. | may have either low or high input impedance |
| Answer» C. has very low input impedance | |
| 741. |
The circuit in figure is |
| A. | rectifier |
| B. | voltage to frequency converter |
| C. | frequency to voltage converter |
| D. | logarithmic amplifier |
| Answer» E. | |
| 742. |
A transistor with a = 0.9 and ICBO = 10 μA is biased so that IBQ = 90 μA. Then ICQ will be |
| A. | 910 mA |
| B. | 5 mA |
| C. | 5.25 mA |
| D. | 4.95 mA |
| Answer» B. 5 mA | |
| 743. |
To obtain very high input and O/P impedance in a feedback amplifier, the type of feedback utilized |
| A. | voltage series |
| B. | current series |
| C. | voltage shunt |
| D. | current shunt |
| Answer» C. voltage shunt | |
| 744. |
In figure, the function of resistor R is |
| A. | to reduce ripples in the output |
| B. | to improve voltage regulation |
| C. | to limit the surge current |
| D. | either (a) or (c) |
| Answer» D. either (a) or (c) | |
| 745. |
The properties of FETs closely resemble those of a |
| A. | thermionic valve |
| B. | P-N-P transistor |
| C. | N-P-N transistor |
| D. | UJT |
| Answer» B. P-N-P transistor | |
| 746. |
For the amplifier circuit of figure, the h parameters of transistor are hib = 25 Ω, hfb = 0.999, hob = 10-6 Ω. The voltage gain is |
| A. | 0.999 |
| B. | 1.98 |
| C. | 20 |
| D. | 400 |
| Answer» E. | |
| 747. |
IF amplifiers for radio receivers are often tuned to |
| A. | 456 Hz |
| B. | 456 kHz |
| C. | 3456 MHz |
| D. | 456 GHz |
| Answer» C. 3456 MHz | |
| 748. |
In figure ID = 4 mA. Then VGS = |
| A. | 4.4 V |
| B. | -4.4 V |
| C. | 0.44 V |
| D. | -0.44 V |
| Answer» C. 0.44 V | |
| 749. |
The output voltage waveform of a CE amplifier is fed to a dc coupled CRO. The trace on the screen will be |
| A. | dc output voltage |
| B. | ac output voltage |
| C. | sum of dc and ac output voltage |
| D. | either (a) or (b) |
| Answer» D. either (a) or (b) | |
| 750. |
The input gate current of FET is closer to |
| A. | few amperes |
| B. | few milli amperes |
| C. | few microamperes |
| D. | negligibly smaller value |
| Answer» E. | |