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.
| 601. |
A D.C. amplifier amplify |
| A. | D.C. only |
| B. | A.C. only |
| C. | both A.C. and D.C. |
| D. | none of the above. |
| Answer» B. A.C. only | |
| 602. |
For maximum unclipped output from a CE amplifier, the Q point should be |
| A. | at the centre of dc load line |
| B. | at the centre of ac load line |
| C. | at the centre of collector current |
| D. | none of the above |
| Answer» C. at the centre of collector current | |
| 603. |
In figure VBE = 0.7 V. The base current is |
| A. | above 97 μA |
| B. | about 97 mA |
| C. | about 75 μA |
| D. | about 75 mA |
| Answer» B. about 97 mA | |
| 604. |
The current through common emitter resistor of a differential amplifier is called |
| A. | differential current |
| B. | emitter current |
| C. | ground current |
| D. | tail current |
| Answer» E. | |
| 605. |
The advantage of Weinbridge oscillator over the phase shift oscillator is that oscillator the frequency may be varied over a range of |
| A. | 0.043055555555556 |
| B. | 0.04375 |
| C. | 0.045138888888889 |
| D. | 0.048611111111111 |
| Answer» E. | |
| 606. |
In op-amp integrating amplifier the input is feed to |
| A. | inverting input |
| B. | non-inverting input |
| C. | both inverting and non-inverting input |
| D. | either inverting or non-inverting input |
| Answer» B. non-inverting input | |
| 607. |
When a transistor is connected in common emitter mode, it with have |
| A. | negligible input resistance and high output resistance |
| B. | high input resistance and low output resistance |
| C. | medium input resistance and high output resistance |
| D. | low input resistance as well as output resistance |
| Answer» D. low input resistance as well as output resistance | |
| 608. |
Two transistors have same value of a but different gain (G) bandwidth (B) product. The transistors have similar geometry. However one of them is germanium and the other is silicon. The transistor with lower GB product |
| A. | is germanium |
| B. | is silicon |
| C. | may be either of two |
| D. | cannot be identified on the basis of above data |
| Answer» C. may be either of two | |
| 609. |
The coupling capacitor mainly affects |
| A. | bandwidth |
| B. | lower cut-off frequency |
| C. | higher cut-off frequency |
| D. | both lower as well as higher cut-off frequency |
| Answer» C. higher cut-off frequency | |
| 610. |
A silicon sample A is doped with 1018 Atoms/cm3 of Boron. Another sample B of identical dimensions is doped with 1018 atoms/cm3 of phosphorus. The ratio of electron to hole mobility is 3. The ratio of conductivity of the sample A to B is |
| A. | 3 |
| B. | 43525 |
| C. | 43526 |
| D. | 43499 |
| Answer» C. 43526 | |
| 611. |
The gain of a source follower is unity. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 612. |
Which of the following couplings may cause unwanted clamping? |
| A. | Resistive |
| B. | Inductive |
| C. | Capacitive |
| D. | Both (a) or (b) |
| Answer» D. Both (a) or (b) | |
| 613. |
The equivalent circuit of an op-amp has |
| A. | a virtual ground at input |
| B. | a virtual ground at output |
| C. | virtual ground at input as well as at output |
| D. | none of the above |
| Answer» B. a virtual ground at output | |
| 614. |
An engineer designs an amplifier to have a voltage gain of 60, but when constructed it only had a gain of 50. How much feedback should be used to provide the desired level? |
| A. | 0.0003 |
| B. | 0.0033 |
| C. | 0.013 |
| D. | 0.033 |
| Answer» C. 0.013 | |
| 615. |
Ac signals are given to both inverting and non-inverting terminals of an op-amp. When will the output maximum |
| A. | when the phase difference between the inputs is 0° |
| B. | when the phase difference between the inputs in 90° |
| C. | when the phase difference between the inputs is 180° |
| D. | when the phase difference between the inputs is 0 or 180° |
| Answer» D. when the phase difference between the inputs is 0 or 180¬∞ | |
| 616. |
The JFET in the circuit shown in figure has an IDSS = 10 mA and Vp = -5V. The value of the resistance Rs for a drain current IDS = 6.4 mA is |
| A. | 156 Ω |
| B. | 470 Ω |
| C. | 560 Ω |
| D. | 1 kΩ |
| Answer» B. 470 Œ© | |
| 617. |
The input and output signals for CE amplifier are always |
| A. | equal |
| B. | in phase |
| C. | out of phase |
| D. | complementary to each other |
| Answer» D. complementary to each other | |
| 618. |
An ideal op-amp requires |
| A. | zero input offset voltage |
| B. | low input offset voltage |
| C. | high input offset voltage |
| D. | infinite input offset voltage |
| Answer» B. low input offset voltage | |
| 619. |
A power transistor dissipates 5 W. If ambient temperature is 30° and case to air thermal resistance is 10° C/W, the case temperature is |
| A. | 80°C |
| B. | 20°C |
| C. | 32°C |
| D. | 305°C |
| Answer» B. 20¬∞C | |
| 620. |
The maximum efficiency of class A amplifier is |
| A. | 1 |
| B. | 0.818 |
| C. | 0.5 |
| D. | 0.4 |
| Answer» D. 0.4 | |
| 621. |
The parameter β of a BJT change by 300%. If self bias is used in the amplifier using this BJT, the quiescent value of IC and VCE remain almost the same. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 622. |
A full wave rectifier using centre tapped transformer and a bridge rectifier use similar diodes and have equal no load output voltage. Under equal load conditions |
| A. | Output voltage of bridge rectifier |
| B. | Output voltage of bridge rectifier will be more than that of other |
| C. | Output voltage of both will be exactly equal |
| D. | Output voltage of any one may be more than that of other |
| Answer» B. Output voltage of bridge rectifier will be more than that of other | |
| 623. |
Which of the following is not valid in case of FETs? |
| A. | It has low voltage gain |
| B. | It has high input impedance |
| C. | It has fast switching time |
| D. | It is voltage controlled device |
| Answer» D. It is voltage controlled device | |
| 624. |
A voltage gain of a CE amplifier connected in collector to base configuration is 50. Collector to base resistor RF = 1 kΩ, RC = 4Ω, the O/P resistance R0 =? |
| A. | 800 Ω |
| B. | 813 Ω |
| C. | 817 Ω |
| D. | 819 Ω |
| Answer» C. 817 Œ© | |
| 625. |
The main advantage of CC amplifier is |
| A. | High input impedance and low output impedance |
| B. | Low input impedance and high output impedance |
| C. | High voltage gain |
| D. | High current gain |
| Answer» B. Low input impedance and high output impedance | |
| 626. |
The upper end of the d.c. load line is called the __________ point and the lower end is the __________ point. |
| A. | cut off, saturation |
| B. | saturation, active |
| C. | saturation, cut off |
| D. | active saturation |
| Answer» D. active saturation | |
| 627. |
A typical value of gm for a FET is about 25 μs. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 628. |
For class B operation the theoretical maximum efficiency is |
| A. | 1 |
| B. | 0.785 |
| C. | 0.5 |
| D. | 0.275 |
| Answer» C. 0.5 | |
| 629. |
In the circuit shown in the figure, the approximate voltage at the transistor, |
| A. | base and emitter respectively are -8 V and -7.3 V |
| B. | base and collector respectively are -8 V and -5 V |
| C. | Collector and emitter respectively are -5 V and -7.3 |
| D. | base, emitter and collector respectively are -8 V, 7.3 V and -5 V |
| Answer» E. | |
| 630. |
Regulation of the DC power supply of 12 V, 100 mA is the effective resistance of power supply is 20 Ω |
| A. | 0.22 |
| B. | 1.31 |
| C. | 0.3 |
| D. | 0.2 |
| Answer» E. | |
| 631. |
A collector collects |
| A. | electrons from the base in case of N-P-N transistor |
| B. | electrons from the emitter in case P-N-P transistor |
| C. | holes from the base in case of N-P-N transistor |
| D. | holes from the base in case of P-N-P transistor |
| Answer» C. holes from the base in case of N-P-N transistor | |
| 632. |
For oscillations to starts, the loop gain A β of the oscillator must be initially |
| A. | less than unity |
| B. | 0.5 |
| C. | 1 |
| D. | more than unity |
| Answer» E. | |
| 633. |
In figure, VG = |
| A. | 2.22 V |
| B. | 22.2 V |
| C. | 0.22 V |
| D. | 0.022 V |
| Answer» B. 22.2 V | |
| 634. |
The disadvantage of direct coupled amplifiers is |
| A. | drift |
| B. | large size of transistor |
| C. | low voltage gain |
| D. | both (b) and (c) |
| Answer» B. large size of transistor | |
| 635. |
Linear transistor circuits always operate in |
| A. | saturation region |
| B. | cut off region |
| C. | active region |
| D. | passive region |
| Answer» D. passive region | |
| 636. |
In a series regulated power supply circuit the voltage gain of pass transistor satisfies the condition |
| A. | Av ‚Üí ‚àû |
| B. | 1 << Av ‚Üí ‚àû |
| C. | Av ≈ 1 |
| D. | Av << 1 |
| Answer» D. Av << 1 | |
| 637. |
Assertion (A): In a push pull circuit each transistor stays in the active region for one half cycleReason (R): A push pull amplifier has low distortion |
| 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 | |
| 638. |
In a BJT CE amplifier circuit the value of coupling capacitor should be such that |
| A. | its reactance is small for the lowest frequency in the input and output |
| B. | its reactance is high for the lowest frequency in the input and output |
| C. | its reactance is zero for the lowest frequency in the input and output |
| D. | its reactance is infinite for the lowest frequency in the input and output |
| Answer» B. its reactance is high for the lowest frequency in the input and output | |
| 639. |
In the circuit of figure for sinusoidal input the waveform of the output will be as shown in |
| A. | figure A |
| B. | figure B |
| C. | figure C |
| D. | figure D |
| Answer» E. | |
| 640. |
For a transistor if adc = 0.98 and emitter current IE is 2 mA, then base current will be |
| A. | 10 μA |
| B. | 40 μA |
| C. | 80 μA |
| D. | 200 μA |
| Answer» B. 40 ŒºA | |
| 641. |
For a sinusoidal input, the circuit shown in the figure will act as a |
| A. | Pulse generator |
| B. | Full wave rectifier |
| C. | Ramp generator |
| D. | Voltage Doubler |
| Answer» C. Ramp generator | |
| 642. |
The heat sink disposes off heat mainly by |
| A. | radiation |
| B. | natural convection |
| C. | forced convection |
| D. | conduction |
| Answer» C. forced convection | |
| 643. |
Which of the following compensation method in amplifier can be used to reduce the bandwidth? |
| A. | Pole-zero compensation |
| B. | Dominant pole compensation |
| C. | Lead compensation |
| D. | Any of the above |
| Answer» C. Lead compensation | |
| 644. |
An npn transistor has a Beta cutoff frequency fβ of 1 MHz, and a common emitter short circuit low frequency current gain β0 of 200. It unity gain frequency fT and the alpha cut off frequency fa2 respectively are |
| A. | 200 MHz, 201 MHz |
| B. | 200 MHz, 199 MHz |
| C. | 199 MHz, 200 MHz |
| D. | 201 MHz, 200 MHz |
| Answer» B. 200 MHz, 199 MHz | |
| 645. |
The emitter resistor RE in the emitter of CE amplifier stabilizes the dc operating point against variation in |
| A. | temperature only |
| B. | β of transistor |
| C. | both temperature and β |
| D. | none of the above |
| Answer» D. none of the above | |
| 646. |
For operation of enhancement only N-channel MOSFET, value of gate voltage has to be |
| A. | zero |
| B. | low positive |
| C. | high negative |
| D. | high positive |
| Answer» E. | |
| 647. |
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 must be the minimum gain of the oscillator to provide oscillations? |
| A. | 40 |
| B. | 60 |
| C. | 100 |
| D. | 130 |
| Answer» B. 60 | |
| 648. |
The most commonly used bias in BJT amplifier circuits is |
| A. | voltage divider bias |
| B. | emitter bias |
| C. | collector bias |
| D. | collector feedback bias |
| Answer» B. emitter bias | |
| 649. |
Common base configuration is little used because |
| A. | it has low input impedance |
| B. | it has high input impedance |
| C. | it does not heat up |
| D. | it has very high gain |
| Answer» B. it has high input impedance | |
| 650. |
Following figure is a signal conditioning Amplifier, changes gain depending upon the polarity of Vs. What will be circuit voltage gain for + Vs and for - Vs if D2 is ideal. |
| A. | AV = -R3/R1 |
| B. | R3/R1 |
| C. | R1/R3 |
| D. | 1 + R3/R1 |
| Answer» B. R3/R1 | |