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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.
| 551. |
When a p-n-p transistor is operating in active region, the current in the n region is due to |
| A. | only holes |
| B. | only electrons |
| C. | mainly holes |
| D. | mainly electrons |
| Answer» D. mainly electrons | |
| 552. |
EG for silicon is 1.12 eV and that for germanium is 0.72 eV. Therefore, it can be concluded that |
| A. | the conductivity of silicon will be less than that of germanium at room temperature |
| B. | the conductivity of silicon will be more than that of germanium at room temperature |
| C. | the conductivity of two will be same at 60°C |
| D. | the conductivity of two will be same at 100°C |
| Answer» B. the conductivity of silicon will be more than that of germanium at room temperature | |
| 553. |
One eV = 1.602 x 10-19 joules. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 554. |
When a p-n-p transistor is properly biased to operate in active region the holes from emitter. |
| A. | diffuse through base into collector region |
| B. | recombine with electrons in base |
| C. | recombine with electrons in emitter |
| D. | none of the above |
| Answer» B. recombine with electrons in base | |
| 555. |
SCR can be turned on by applying anode voltage at a sufficient fast rateapplying sufficiently large anode voltageincreasing the temperature of SCR to a sufficientlyapplying sufficiently large gate current. |
| A. | 1, 2, 4 only |
| B. | 4 only |
| C. | 1, 2, 3, 4 |
| D. | none |
| Answer» D. none | |
| 556. |
In the forward blocking region of a silicon, controlled rectifier, the SCR is |
| A. | in the off-state |
| B. | in the ON state |
| C. | reverse biased |
| D. | at the point of breakdown |
| Answer» B. in the ON state | |
| 557. |
In p channel JFET, VGS is positive. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 558. |
Assertion (A): In design of circuit using BJT, a derating factor is used. Reason (R): As the ambient temperature increases, heat dissipation becomes slower. |
| 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 | |
| 559. |
In which mode of BJT operation are both junctions forward biased? |
| A. | Active |
| B. | Saturation |
| C. | Cut off |
| D. | Reverse active |
| Answer» C. Cut off | |
| 560. |
The impurity added to extrinsic semiconductor is of the order of |
| A. | 1 in 100 |
| B. | 1 in 1000 |
| C. | 1 in 100, 0000 |
| D. | 1 in 100, 000, 000 |
| Answer» C. 1 in 100, 0000 | |
| 561. |
In active filter circuits, inductances are avoided mainly because they |
| A. | are always associated with some resistance |
| B. | are bulky and unsuitable for miniaturisation |
| C. | are non-linear in nature |
| D. | saturate quickly |
| Answer» C. are non-linear in nature | |
| 562. |
Which of the following is a passive component? |
| A. | Semiconductor devices |
| B. | Vacuum tube devices |
| C. | Capacitors |
| D. | All of the above |
| Answer» D. All of the above | |
| 563. |
Which of these has semi-conductor metal junction? |
| A. | PIN diode |
| B. | Photo diode |
| C. | Tunnel diode |
| D. | Schottky diode |
| Answer» E. | |
| 564. |
The conduction band is |
| A. | same as forbidden energy gap |
| B. | generally located on the top of the crystal |
| C. | generally located on the bottom of the crystal |
| D. | a range of energies corresponding to the energies of the free electrons |
| Answer» E. | |
| 565. |
Junction temperature is always the same as room temperature. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 566. |
Materials in order of decreasing electrical conductivity are |
| A. | aluminium, silver, gold, copper |
| B. | gold, silver, copper, aluminium |
| C. | copper, silver, gold, aluminium |
| D. | silver, copper, gold, aluminium |
| Answer» E. | |
| 567. |
Assertion (A): When forward biased a p-n junction has low resistance. Reason (R): The ratio is called dynamic resistance. |
| 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 | |
| 568. |
Figure shows characteristics curves for bipolar transistor. These curves are |
| A. | output characteristics of n-p-n transistor (common base) |
| B. | output characteristics of p-n-p transistor (common base) |
| C. | output characteristics of n-p-n transistor (common emitter) |
| D. | output characteristics of p-n-p transistor (common emitter) |
| Answer» C. output characteristics of n-p-n transistor (common emitter) | |
| 569. |
Consider the following statements.The functions of an oxide layer in an IC device is to mask against diffusion or ion implantinsulate the surface electricallyincrease the melting point of siliconproduce a chemically stable protective layer of these statements. |
| A. | 1, 2, 3 |
| B. | 1, 3, 4 |
| C. | 2, 3, 4 |
| D. | 1, 2, 4 |
| Answer» E. | |
| 570. |
A-P type material has an acceptor ion concentration of 1 x 1016 per cm3. Its intrinsic carrier concentration is 1.48 x 1010/ cm. The hole and electron mobilities are 0.05m2/V-sec and 0.13 m2/V-sec respectively calculate the resistivity of the material |
| A. | 12.5 Ω-cm |
| B. | 1.25 Ω-cm |
| C. | 0.125 Ω-cm |
| D. | 125 Ω-cm |
| Answer» C. 0.125 Œ©-cm | |
| 571. |
The kinetic energy of photoelectrons emitted by a photo sensitive surface depends on |
| A. | intensity of the incident radiation |
| B. | wavelength of the incident radiation |
| C. | surface conditions of the surface |
| D. | angle of incidence of radiation |
| Answer» C. surface conditions of the surface | |
| 572. |
The factor n in the equation for calculating current for a silicon diode is |
| A. | 1 |
| B. | 2 |
| C. | 2.5 |
| D. | 2 for low levels of current and 1 for high levels of current |
| Answer» E. | |
| 573. |
A sample of N type semiconductor has electron density of 6.25 x 108/cm2 at 300 K. If the intrinsic concentration of carriers in this sample is 2.5 x 1013/cm3 at this temperature, the hole density works out to be |
| A. | 106/cm3 |
| B. | 108/cm3 |
| C. | 1010/cm3 |
| D. | 10l2/cm3 |
| Answer» C. 1010/cm3 | |
| 574. |
The forbidden energy gap between the valence band and conduction band will be wide in case of |
| A. | semiconductors |
| B. | all metals |
| C. | good conductors of electricity |
| D. | insulators |
| Answer» E. | |
| 575. |
In p type semiconductor holes are majority carriers. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 576. |
In a solar cell, the photovoltaic voltages is the voltage at which the resultant current is |
| A. | positive |
| B. | zero |
| C. | negative |
| D. | rated current |
| Answer» C. negative | |
| 577. |
Assertion (A): The behaviour of FET is similar to that of a pentode. Reason (R): FETs and vacuum triode are voltage controlled devices. |
| 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 | |
| 578. |
When a p-n junction is reverse biased |
| A. | holes and electrons move away from the junction |
| B. | holes and electrons move towards the junction |
| C. | holes move towards junction and electrons move away from junction |
| D. | holes move away from junction and electrons move towards junction |
| Answer» B. holes and electrons move towards the junction | |
| 579. |
If too large current passes through the diode |
| A. | all electrons will leave |
| B. | all holes will freeze |
| C. | excessive heat may damage the diode |
| D. | diode will emit light |
| Answer» D. diode will emit light | |
| 580. |
Avalanche beakdown is primarily dependent on the phenomenon of |
| A. | doping |
| B. | collision |
| C. | recombination |
| D. | ionization |
| Answer» C. recombination | |
| 581. |
In n channel JFET |
| A. | ID and VDS are positive but VGS is negative |
| B. | ID and VGS are positive but VDS is negative |
| C. | VDS and VGS are positive but ID is negative |
| D. | ID, VDS and VGS are all positive |
| Answer» B. ID and VGS are positive but VDS is negative | |
| 582. |
Assertion (A): The amount of photoelectric emission depends on the intensity of incident light. Reason (R): Photo electric emission can occur only if frequency of incident light is less than threshold frequency. |
| 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» D. A is false but R is true | |
| 583. |
A varactor diode is |
| A. | reverse biased |
| B. | forward biased |
| C. | biased to breakdown |
| D. | unbiased |
| Answer» B. forward biased | |
| 584. |
The unit of thermal resistance of a semi-conductor device is |
| A. | Ohms |
| B. | Ohms/°C |
| C. | °C/ohm |
| D. | °C/watt |
| Answer» E. | |
| 585. |
A doped semi-conductor is called |
| A. | impure semi-conductor |
| B. | dipole semi-conductor |
| C. | bipolar semi-conductor |
| D. | extrinsic semi-conductor |
| Answer» E. | |
| 586. |
The energy to cause thermionic emission is supplied by heating the cathode. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 587. |
For a BJT, under the saturation region. |
| A. | IC = βIB |
| B. | IC > βIB |
| C. | IC is independent of other parameter |
| D. | IC < βIB |
| Answer» E. | |
| 588. |
Which of the following are voltage controlled devices? |
| A. | Vacum triode |
| B. | FET |
| C. | SCR |
| D. | Both (a) and (b) |
| Answer» E. | |
| 589. |
The v-i characteristic of an element is shown in below figure the element is |
| A. | non-linear, active, non-bilateral |
| B. | linear, active, non-bilateral |
| C. | non-linear, passive, non-bilateral |
| D. | non-linear, active, bilateral |
| Answer» E. | |
| 590. |
Assertion (A): JFET is a voltage controlled device. Reason (R): The drain current can be controlled by controlling VGS. |
| 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 | |
| 591. |
The charge of an electron is |
| A. | 1.6 x 10-17 coulomb |
| B. | 1.6 x 10-19 coulomb |
| C. | 1.6 x 10-21 coulomb |
| D. | 1.6 x 10-23 coulomb |
| Answer» C. 1.6 x 10-21 coulomb | |
| 592. |
Assertion (A): Tunnel diode is used in many pulse and digital circuits. Reason (R): The v-i curve of a tunnel diode resembles letter 'N'. |
| 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 | |
| 593. |
The threshold voltage of a MOSFET can be lowered by using thin gate oxidereducing the substrate concentrationincreasing the substrate concentration. Of the above statement |
| A. | 3 alone is correct |
| B. | 1 and 2 are correct |
| C. | 1 and 3 are correct |
| D. | 2 alone is correct |
| Answer» D. 2 alone is correct | |
| 594. |
The range of life time carriers (electrons and holes) is |
| A. | 1 μs to 100 μs |
| B. | 1 nano sec to 1 μs |
| C. | 1 nano sec to hundreds of μs |
| D. | none of the above |
| Answer» D. none of the above | |
| 595. |
If the energy gap of a semiconductor is 1.1 eV, then it would be. |
| A. | opaque to the visible light |
| B. | transparent to the visible light |
| C. | transparent to the ultraviolet radiation |
| D. | opaque to the infrared radiation |
| Answer» B. transparent to the visible light | |
| 596. |
Which of the following is used in the sterilization of water? |
| A. | Hydrogen bromide |
| B. | Oxygen |
| C. | Ozone |
| D. | Caustic potash |
| Answer» D. Caustic potash | |
| 597. |
Which of these has highly doped p and n region? |
| A. | PIN diode |
| B. | Tunnel diode |
| C. | Schottky diode |
| D. | Photodiode |
| Answer» C. Schottky diode | |
| 598. |
If the drift velocity of holes under a field gradient of 100 V/m in 5 m/s, their mobility (in SI units) is |
| A. | 0.05 |
| B. | 0.5 |
| C. | 50 |
| D. | 500 |
| Answer» B. 0.5 | |
| 599. |
The current density J, free electron mobility μn, hole mobility μp , magnitude of free electron and hole concentration ni electric field E and charge on electron e, in intrinsic semiconductor are related as |
| A. | J = (μn + μp)eniE |
| B. | J = |
| C. | J = |
| D. | J = |
| Answer» B. J = | |
| 600. |
The permeability of soft iron can be increased by |
| A. | purifying it |
| B. | reducing carbon percentage |
| C. | alloying with cobalt |
| D. | increasing percentage |
| Answer» D. increasing percentage | |