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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.
| 601. |
Photoconductive devices uses |
| A. | metallic conductors |
| B. | good quality insulators |
| C. | semiconductors |
| D. | either (a) or (c) |
| Answer» D. either (a) or (c) | |
| 602. |
The dynamic resistance of a forward biased p-n diode |
| A. | varies inversely with current |
| B. | varies directly with current |
| C. | is constant |
| D. | is either constant or varies directly with current |
| Answer» B. varies directly with current | |
| 603. |
A Schottky diode clamp is used along with switching BJT for |
| A. | reducing the power dissipation |
| B. | reducing the switching time |
| C. | increasing the value of β |
| D. | reducing the base current |
| Answer» C. increasing the value of Œ≤ | |
| 604. |
Silicon diodes have __________ reverse resistance than germanium diodes. |
| A. | a much smaller |
| B. | a much larger |
| C. | an infinite |
| D. | a negligible |
| Answer» C. an infinite | |
| 605. |
An enhancement mode MOSFET is on when the gate voltage is |
| A. | zero |
| B. | positive |
| C. | high |
| D. | more threshold value |
| Answer» E. | |
| 606. |
When a BJT is operated under saturated condition |
| A. | both junctions are forward biased |
| B. | both junctions are reverse biased |
| C. | CB junction is forward biased and EB junction is reverse biased |
| D. | EB junction is forward biased and CB junction is reverse biased |
| Answer» B. both junctions are reverse biased | |
| 607. |
Which one of the following gain equations is correct for a MOSFET common-source amplifier?(gm is mutual conductance, and RD is load resistance at the drain) |
| A. | AV = gm/(1 - RD) |
| B. | AV = gm/RD |
| C. | AV = gm/(1 + RD) |
| D. | AV = RD/gm |
| Answer» C. AV = gm/(1 + RD) | |
| 608. |
Transconductance characteristics of JFET depict the relation between |
| A. | ID and VGS for different value of VDS |
| B. | ID and VDS for different value of VGS |
| C. | VGS and VDS for different values of ID |
| D. | VDS and ID for different values of VGS |
| Answer» B. ID and VDS for different value of VGS | |
| 609. |
In given figure a silicon diode is carrying a constant current of 1 mA. When the temperature of the diode is 20°C, VD is found to be 700 mV. If the temperature rises to 40°C, VD becomes approximately equal to |
| A. | 747 mV |
| B. | 660 mV |
| C. | 680 mV |
| D. | 700 mV |
| Answer» B. 660 mV | |
| 610. |
Assertion (A): Two transistors one n-p-n and the other p-n-p are identical in all respects (doping, construction, shape, size). The n-p-n transistor will have better frequency response. Reason (R): The electron mobility is higher than hole mobility. |
| 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 | |
| 611. |
In a half wave rectifier, the load current flows |
| A. | only for the positive half cycle of the input signal |
| B. | only for the negative half cycle of the input signal |
| C. | for full cycle |
| D. | for less than fourth cycle |
| Answer» B. only for the negative half cycle of the input signal | |
| 612. |
A silicon diode is forward biased and total applied voltage is 5 V. The voltage across p-n junction is |
| A. | 5 V |
| B. | Slightly less than 5 V |
| C. | 0.7 V |
| D. | 0 |
| Answer» D. 0 | |
| 613. |
In LED the radiation is in |
| A. | visible region |
| B. | infrared region |
| C. | both (a) and (b) |
| D. | neither (a) nor (b) |
| Answer» E. | |
| 614. |
A metal loses electrons at room temperature. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 615. |
The inductance of a single layer solenoid of 10 turns is 5 μH. Which one of the following is the correct value of inductance when the number of turns is 20 and the length is doubled. |
| A. | 10 μH |
| B. | 20 μH |
| C. | 40 μH |
| D. | 5 μH |
| Answer» B. 20 ŒºH | |
| 616. |
For insulators the energy gap is of the order of |
| A. | 0.1 eV |
| B. | 0.7 eV |
| C. | 1.1 eV to 1.2 eV |
| D. | 5 to 15 eV |
| Answer» E. | |
| 617. |
Hall coefficient KH and charge density r are related as |
| A. | KH = |
| B. | KH = r |
| C. | KH = |
| D. | KH = (r)1.2 |
| Answer» B. KH = r | |
| 618. |
Assertion (A): In an n-p-n transistor as the electrons enter the collector region, they are accelerated towards the collector terminal. Reason (R): Emitter base junction in BJT is forward biased. |
| 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 | |
| 619. |
A P-N junction offers |
| A. | high resistance in forward as well as reverse direction |
| B. | low resistance in forward as well as reverse direction |
| C. | conducts in forward direction only |
| D. | conducts in reverse direction only |
| Answer» D. conducts in reverse direction only | |
| 620. |
The number of p-n junctions in a semiconductor diode are |
| A. | 0 |
| B. | 1 |
| C. | 2 |
| D. | 1 or 2 |
| Answer» C. 2 | |
| 621. |
Which of the following is an active device? |
| A. | Transformer |
| B. | Silicon controlled rectifier |
| C. | Electric bulb |
| D. | Loudspeaker |
| Answer» C. Electric bulb | |
| 622. |
If a sample of Ge and a sample of Si have the same impurity density are kept at room temperature |
| A. | both will have equal value of resistivity |
| B. | both will have equal - ve of resistivity |
| C. | resistivity of germanium will be higher than that of silicon |
| D. | resistivity of silicon will be higher than of Ge |
| Answer» E. | |
| 623. |
As temperature increases |
| A. | the forbidden energy gap in silicon and germanium increase |
| B. | the forbidden energy gap in silicon and germanium decrease |
| C. | the forbidden energy gap in silicon decreases while that in germanium decreases |
| D. | the forbidden energy gap in silicon increases while that in germanium decreases |
| Answer» C. the forbidden energy gap in silicon decreases while that in germanium decreases | |
| 624. |
In a JFET |
| A. | the source gate junction is forward biased and gate drain junction is reverse biased |
| B. | both the junctions are forward biased |
| C. | both the junctions are reverse biased |
| D. | the source gate junction is reverse biased and gate drain junction is forward biased |
| Answer» D. the source gate junction is reverse biased and gate drain junction is forward biased | |
| 625. |
Assertion (A): A decrease in temperature increases the reverse saturation current in a p-n diode. Reason (R): When a diode is reverse biased surface leakage current flows. |
| 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» E. | |
| 626. |
A semiconductor in its purest form called |
| A. | intrinsic semiconductor |
| B. | extrinsic semiconductor |
| C. | P-type semiconductor |
| D. | N-type semiconductor |
| Answer» B. extrinsic semiconductor | |
| 627. |
In monostable multivibrator |
| A. | has no stable state |
| B. | has one stable state |
| C. | has two stable states |
| D. | switches automatically from one state to other state |
| Answer» C. has two stable states | |
| 628. |
At room temperature, the current in the, intrinsic semiconductor is due to |
| A. | holes |
| B. | electrons |
| C. | ions |
| D. | holes and electrons |
| Answer» E. | |
| 629. |
For a photoconductor with equal electron and hole mobilities and perfect ohmic contacts at the ends, an increase in illumination results in |
| A. | a change in O.C. voltage |
| B. | a change in S.C. current |
| C. | a decrease in resistance |
| D. | an increase in resistance |
| Answer» D. an increase in resistance | |
| 630. |
Which is correct for a vacuum triode? |
| A. | μ = rpgm |
| B. | rp = μgm |
| C. | gm = μrp |
| D. | rpgm |
| Answer» C. gm = Œºrp | |
| 631. |
On which of the following effect do thermocouples work? |
| A. | Thomson effect |
| B. | Seeback effect |
| C. | Peltier effect |
| D. | Joule effect |
| Answer» C. Peltier effect | |
| 632. |
What is the necessary a.c. input power from the transformer secondary used in a half wave rectifier to deliver 500 W of d.c. power to the load? |
| A. | 1232 W |
| B. | 848 W |
| C. | 616 W |
| D. | 308 W |
| Answer» B. 848 W | |
| 633. |
Thermal runaway is not possible in FET, because as the temperature of FET increases. |
| A. | the mobility decreases |
| B. | the transconductance increases |
| C. | impedance of the source |
| D. | power dissipation in the chip |
| Answer» C. impedance of the source | |
| 634. |
Which of the following has highest conductivity? |
| A. | Silver |
| B. | Aluminium |
| C. | Tungsten |
| D. | Platinum |
| Answer» B. Aluminium | |
| 635. |
The ripple factor of power supply is a measure of |
| A. | its filter efficiency |
| B. | diode rating |
| C. | its voltage regulation |
| D. | purity of power output |
| Answer» E. | |
| 636. |
Which of the following characteristics of a silicon p-n junction diode make it suitable for use as ideal diode? It has low saturation current.It has high value of cut in voltage.It can withstand large reverse voltage.When compared with germanium diode, silicon diode shows a lower degree of temperature dependence under reverse conditions. Select the answer using the given below |
| A. | 1 and 2 |
| B. | 1, 2, 3, 4 |
| C. | 2, 3, 4 |
| D. | 1, 3 |
| Answer» C. 2, 3, 4 | |
| 637. |
The presence of some holes in an intrinsic semiconductor at room temperature is due to |
| A. | valence electrons |
| B. | doping |
| C. | free electrons |
| D. | thermal energy |
| Answer» E. | |
| 638. |
Hay bridge is suitable for measuring inductance of which one of the following inductors? |
| A. | Having Q value less than 10 |
| B. | Having Q value greater than 10 |
| C. | Having any value of Q |
| D. | Having phase angle of reactance very large |
| Answer» C. Having any value of Q | |
| 639. |
The voltage across the secondary of the transformer in a half wave rectifier (without any filter circuit) is 25 volts. The maximum voltage on the reverse biased diode will be |
| A. | 100 V |
| B. | 50 V |
| C. | 25 V |
| D. | 12.5 V |
| Answer» D. 12.5 V | |
| 640. |
Measurement of Hall coefficient enables the determination of |
| A. | recovery time of stored carrier |
| B. | type of conductivity and concentration of charge carriers |
| C. | temperature coefficient and thermal conductivity |
| D. | Fermi level and forbidden energy gap |
| Answer» C. temperature coefficient and thermal conductivity | |
| 641. |
Choose proper substitutes for x and y to make the following statement correct.Tunnel diode, Avalanche photodiode are operated in x bias and y bias respectively. |
| A. | x : Reverse, y : Reverse |
| B. | x : Reverse, y : forward |
| C. | x : Forward, y : Reverse |
| D. | x : forward, y : forward |
| Answer» D. x : forward, y : forward | |
| 642. |
The voltage across a zener diode |
| A. | is constant in forward direction |
| B. | is constant in reverse direction |
| C. | is constant in both forward and reverse directions |
| D. | none of the above |
| Answer» C. is constant in both forward and reverse directions | |
| 643. |
Which one of the following is not a characteristic of a ferroelectric material? |
| A. | High dielectric constant |
| B. | No hysteresis |
| C. | Ferroelectric characteristic only above the curie point |
| D. | Electric dipole moment |
| Answer» D. Electric dipole moment | |
| 644. |
R.M.S. value of the waveform shown will be |
| A. | 3.53 V |
| B. | 1 V |
| C. | 7.07 V |
| D. | 8.56 V |
| Answer» D. 8.56 V | |
| 645. |
If the gate of JFET is reverse biased, the width of depletion region |
| A. | becomes zero |
| B. | is uniform |
| C. | is more near the source |
| D. | is more near the drain |
| Answer» E. | |
| 646. |
Which of these is used in seven segment display? |
| A. | PIN diode |
| B. | LED |
| C. | Photo diode |
| D. | Tunnel diode |
| Answer» C. Photo diode | |
| 647. |
When avalanche breakdown occurs covalent bonds are not affected. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 648. |
As the reverse voltage is increased, the depletion layer |
| A. | becomes narrow |
| B. | widens |
| C. | remains the same |
| D. | reduce to zero |
| Answer» C. remains the same | |
| 649. |
Epitaxial growth is used in ICs |
| A. | because it produces low parasitic capacitance |
| B. | because it yields back to back isolating pn Junction |
| C. | to grow single crystal n doped silicon on a single crystal P-type substrate |
| D. | to grow Selectivity single crystal P doped silicon of one resistivity on a P type substrate of a different resistivity |
| Answer» E. | |
| 650. |
Hystresis loss least depends on |
| A. | frequency |
| B. | magnetic field intensity |
| C. | volume of the material |
| D. | grain orientation of material |
| Answer» E. | |