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MCQOPTIONS
This section includes 1017 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.
| 801. |
What is the correct sequence of the following step in the fabrication of a monolithic, Bipolar junction transistor? Emitter diffusionBase diffusionBuried layer formationE pi-layer formation Select the correct answer using the codes given below: |
| A. | 3, 4, 1, 2 |
| B. | 4, 3, 1, 2 |
| C. | 3, 4, 2, 1 |
| D. | 4, 3, 2, 1 |
| Answer» E. | |
| 802. |
The main purpose of using transformer coupling in a class A amplifier is to make it more |
| A. | efficient |
| B. | less costly |
| C. | less bulky |
| D. | distortion free |
| Answer» E. | |
| 803. |
Ferrite have |
| A. | low copper loss |
| B. | low eddy current loss |
| C. | low resistivity |
| D. | higher specific gravity compared to iron |
| Answer» D. higher specific gravity compared to iron | |
| 804. |
The output characteristics of a bipolar transistor has three distinct regions. They are known as |
| A. | saturation region, active region and breakdown region |
| B. | inactive region, active region and breakdown region |
| C. | inactive region, saturation region and active region |
| D. | inactive region, saturation region and breakdown region |
| Answer» B. inactive region, active region and breakdown region | |
| 805. |
In n channel JFET, the gate voltage is made more negative |
| A. | the channel width will increase |
| B. | the channel width will decrease |
| C. | the channel width and drain current will decrease |
| D. | the channel width will decrease and drain current will increase |
| Answer» D. the channel width will decrease and drain current will increase | |
| 806. |
Determine the transistor capacitance of a diffused junction varicap diode of a reverse potential of 4.2 V if C(0) = 80 pf and VT = 0.7 V |
| A. | 42 pf |
| B. | 153.03 pf |
| C. | 13.33 pf |
| D. | Data inadequate |
| Answer» B. 153.03 pf | |
| 807. |
The amount of photoelectric emission current depends on |
| A. | frequency of incident radiation |
| B. | intensity of incident radiation |
| C. | both frequency and intensity of incident radiation |
| D. | none of the above |
| Answer» C. both frequency and intensity of incident radiation | |
| 808. |
Resistivity of carbon is around |
| A. | 10 to 70 m-ohm-cm |
| B. | 80 to 130 m-ohm-cm |
| C. | 800 to 1300 m-ohm-cm |
| D. | 8000 to 13000 m-ohm-cm |
| Answer» D. 8000 to 13000 m-ohm-cm | |
| 809. |
The turn on time of an SCR is 5 micro second. Its trigger pulse should have |
| A. | short rise time with pulse width = 2.5 μs |
| B. | long rise time with pulse width = 3 μs |
| C. | short rise time with pulse width = 4 μs |
| D. | long rise time with pulse width = 4 μs |
| Answer» D. long rise time with pulse width = 4 Œºs | |
| 810. |
An one sided abrupt junction has 1021/m3 of dopants on the lightly doped side, zero bias voltage and a built-in potential of 0.2 V. The depletion width of abrupt junction.(q = 1.6 x 10-19 C, εr =16, ε0 = 8.87 x 10-12 F/m) is |
| A. | 0.036 nm |
| B. | 0.6 μm |
| C. | 3 mm |
| D. | 1.5 mm |
| Answer» C. 3 mm | |
| 811. |
Assertion (A): In a Schottky diode the reverse recovery time is almost zero. Reason (R): A Schottky diode has aluminium silicon junction. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 812. |
Which of the following exhibits negative resistance in a portion of its characteristics? |
| A. | Tunnel diode |
| B. | Zener diode |
| C. | JFET |
| D. | MOSFET and tunnel diode |
| Answer» B. Zener diode | |
| 813. |
What is the function of silicon dioxide layer in MOSFETS? |
| A. | To provide high input resistance |
| B. | To increase current carriers |
| C. | To provide high output resistance |
| D. | Both (a) and (c) |
| Answer» B. To increase current carriers | |
| 814. |
Which rectifier has the best ratio of rectification? |
| A. | Half wave rectifier |
| B. | Full wave rectifier |
| C. | Bridge rectifier |
| D. | Three phase full wave rectifier |
| Answer» E. | |
| 815. |
The current due to thermionic emission is given by Richardson Dushman equation. |
| A. | 1 |
| B. | |
| C. | Fermi-Dirac distribution |
| D. | Maxwell's equation |
| Answer» B. | |
| 816. |
Assertion (A): When a high reverse voltage is applied to a p-n junction the diode breaks down. Reason (R): High reverse voltage causes Avalanche effect. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 817. |
The term efficacy, is defined by |
| A. | same as efficiency |
| B. | measure of the ability of a device to produce a desired effect |
| C. | input/output |
| D. | (efficiency)2 |
| Answer» C. input/output | |
| 818. |
If E is energy level of electron and EF is fermi level, and T = 0 and E > EF, then |
| A. | the probability of finding an occupied quantum state of energy higher than EF is zero |
| B. | all quantum states with energies greater than EF are occupied |
| C. | some quantum states with energies greater than EF are occupied |
| D. | majority of quantum states with energies greater than EF are occupied |
| Answer» B. all quantum states with energies greater than EF are occupied | |
| 819. |
Electric breakdown strength of a material depends on its |
| A. | composition |
| B. | moisture content |
| C. | thickness |
| D. | all of the above |
| Answer» E. | |
| 820. |
An amplifier with resistive -ve feedback has two left poles in its open loop transfer function. The amplifier |
| A. | will always be unstable at high frequencies |
| B. | will be stable for all frequencies |
| C. | may be unstable, depending on the feedback factor |
| D. | will oscillate at low frequencies |
| Answer» C. may be unstable, depending on the feedback factor | |
| 821. |
In an intrinsic semiconductor, the intrinsic charge concentration at any absolute temperature T is proportional to |
| A. | T |
| B. | T2 |
| C. | T3 |
| D. | T4 |
| Answer» D. T4 | |
| 822. |
The material which has zero temperature coefficient of resistance is |
| A. | manganin |
| B. | porcelain |
| C. | carbon |
| D. | aluminium |
| Answer» B. porcelain | |
| 823. |
The mean free path of conduction electrons in copper is about 4 x 10-8 m. For a copper block, find the electric field which can give, on an average, 1 eV energy to a conduction electron |
| A. | 2.62 x 107 V/m |
| B. | 2.64 x 107 V/m |
| C. | 2.5 x 107 V/m |
| D. | 2.58 x 107 V/m |
| Answer» D. 2.58 x 107 V/m | |
| 824. |
The minority carrier life time and diffusion constant in a semiconductor material are respectively 100 microsecond and 100 cm2/sec. The diffusion length is |
| A. | 0.1 cm |
| B. | 0.01 cm |
| C. | 0.0141 cm |
| D. | 1 cm |
| Answer» B. 0.01 cm | |
| 825. |
In a photodiode the current is due to |
| A. | majority carriers |
| B. | minority carriers |
| C. | both majority and minority carriers |
| D. | either (a) or (b) |
| Answer» C. both majority and minority carriers | |
| 826. |
Consider the following statements Acceptor level lies close the valence band.Donor level lies close to the valence band.n type semiconductor behaves as an insulator at 0 K.p type semiconductor behaves as an insulator at 0 K. Of these statements: |
| A. | 2 and 3 are correct |
| B. | 1 and 3 are correct |
| C. | 1 and 4 are correct |
| D. | 3 and 4 are correct |
| Answer» D. 3 and 4 are correct | |
| 827. |
No load d.c. output will be least in case of |
| A. | half wave rectifier |
| B. | full wave rectifier |
| C. | bridge rectifier |
| D. | three phase full wave rectifier |
| Answer» B. full wave rectifier | |
| 828. |
Assertion (A): In n-p-n transistor conduction is mainly due to electrons. Reason (R): In n type materials electrons are majority carriers. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 829. |
In a p-n-p transistor operating in forward active mode |
| A. | base is positive with respect to emitter and collector |
| B. | base is negative with respect to emitter and collector |
| C. | emitter is positive with respect to base and base is positive with respect to collector |
| D. | emitter is negative with respect to base and base is positive with respect to collector |
| Answer» D. emitter is negative with respect to base and base is positive with respect to collector | |
| 830. |
The normal operation of JFET is |
| A. | constant voltage region |
| B. | constant current region |
| C. | both constant voltage and constant current regions |
| D. | either constant voltage or constant current region |
| Answer» C. both constant voltage and constant current regions | |
| 831. |
In the sale of diamonds the unit of weight is carat. One carat is equal to |
| A. | 100 mg |
| B. | 150 mg |
| C. | 200 mg |
| D. | 500 mg |
| Answer» D. 500 mg | |
| 832. |
Which of the following semi-conductor has forbidden energy gap less 1 eV? |
| A. | Sulphur |
| B. | Phosphorous |
| C. | Germanium |
| D. | Carbon |
| Answer» D. Carbon | |
| 833. |
Assertion (A): The reverse current in a p-n junction is nearly constant. Reason (R): The reverse breakdown voltage of a p-n diode depends on the extent of doping. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» C. A is true but R is false | |
| 834. |
In which material do conduction and valence bands overlap |
| A. | insulators |
| B. | conductors |
| C. | both conductor and semiconductor |
| D. | semiconductors |
| Answer» C. both conductor and semiconductor | |
| 835. |
Photoelectric effect occurs only in semiconductors and not in metals. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 836. |
Consider the following statements An iron cored choke is a nonlinear device.A carbon resistor kept in a sunlight is a time - invariant and passive device.A dry cell is a time - varying and active device.An air capacitor is a time - invariant and passive device Of these statements |
| A. | 1, 2, 3 and 4 are correct |
| B. | 1, 2 and 3 are correct |
| C. | 1, 2 and 4 are correct |
| D. | 2 and 4 are correct |
| Answer» B. 1, 2 and 3 are correct | |
| 837. |
The dc output voltage from a power supply |
| A. | increases with higher values of filter capacitance and decreases with more load current |
| B. | decreases with higher values of filter capacitance and increases with more load current |
| C. | decreases with higher values of filter capacitance as well as with more load current |
| D. | increases with higher values of filter capacitance as well as with more load current |
| Answer» B. decreases with higher values of filter capacitance and increases with more load current | |
| 838. |
When a ferromagnetic substance is magnetised, there are small changes in its dimensions. This phenomenon is called |
| A. | hysteresis |
| B. | magnetostriction |
| C. | diamagnetism |
| D. | bipolar relaxation |
| Answer» C. diamagnetism | |
| 839. |
As compared to an ordinary semiconductor diode, a Schottky diode |
| A. | has lower cut in voltage |
| B. | has higher cut in voltage |
| C. | lower reverse saturation current |
| D. | both (b) and (c) |
| Answer» B. has higher cut in voltage | |
| 840. |
An increase in temperature increases the width of depletion layer. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 841. |
An air gap provided in the iron core of an inductor prevents |
| A. | flux leakage |
| B. | hysteresis loss |
| C. | core saturation |
| D. | heat generation |
| Answer» D. heat generation | |
| 842. |
In a bipolar transistor which current is smallest |
| A. | collector current |
| B. | base current |
| C. | emitter current |
| D. | any of the three currents |
| Answer» C. emitter current | |
| 843. |
Which of the following has highest resistivity? |
| A. | Mica |
| B. | Paraffin wax |
| C. | Air |
| D. | Mineral oil |
| Answer» D. Mineral oil | |
| 844. |
A Si sample is doped with a fixed number of group N impurities. The electron density n is measured from 4 K to 1200 k for the sample. Which one of the following is correct? |
| A. | n remains constant over the temperature range |
| B. | n increases monotonicaliy with increasing temp |
| C. | n increases first remains constant over a range and again increases with increasing temperature |
| D. | n increases show a peak and then decrease with temperature |
| Answer» C. n increases first remains constant over a range and again increases with increasing temperature | |
| 845. |
When diodes are connected in series to increase voltage rating the peak inverse voltage per junction |
| A. | should not exceed half the breakdown voltage |
| B. | should not exceed the breakdown voltage |
| C. | should not exceed one third the breakdown voltage |
| D. | may be equal to or less than breakdown voltage |
| Answer» D. may be equal to or less than breakdown voltage | |
| 846. |
Electrons can be emitted from a metal surface due to high electric field. |
| A. | 1 |
| B. | |
| C. | 0.35 eV below conduction band |
| D. | about 0.32 eV below conduction band |
| Answer» B. | |
| 847. |
Highest resistivity of the following is |
| A. | nichrome |
| B. | constantan |
| C. | metal |
| D. | manganin |
| Answer» B. constantan | |
| 848. |
Generally, the gain of a transistor amplifier falls at high frequency due to the |
| A. | internal capacitance of the device |
| B. | coupling capacitor at the I/P |
| C. | skin effect |
| D. | coupling capacitor at the O/P |
| Answer» B. coupling capacitor at the I/P | |
| 849. |
When the light falling on a photodiode increases, the reverse minority current |
| A. | increases |
| B. | increases or decreases |
| C. | decreases |
| D. | remains the same |
| Answer» B. increases or decreases | |
| 850. |
The I/P impedance (Zi) and the O/P impedance (Zo) of an ideal trans conductance (Voltage controlled current source) amplifier are |
| A. | Zi = 0, Zo = 0 |
| B. | Zi = 0, Zo = ‚àû |
| C. | Zi = ‚àû, Zo = 0 |
| D. | Zi = ‚àû, Zo = ‚àû |
| Answer» E. | |