MCQOPTIONS
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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.
| 501. |
At absolute zero temperature a semiconductor behaves like |
| A. | an insulator |
| B. | a super conductor |
| C. | a good conductor |
| D. | a variable resistor |
| Answer» B. a super conductor | |
| 502. |
In photo electric emission, the threshold frequency f0, work function Uw, and Planck's constant h are related as |
| A. | |
| B. | |
| Answer» B. | |
| 503. |
A bistable multivibrator |
| A. | has no stable state |
| B. | has one stable state |
| C. | has two stable state |
| D. | none of the above |
| Answer» D. none of the above | |
| 504. |
The spins in a ferrimagnetic material are |
| A. | all aligned parallel |
| B. | partially aligned antiparallel without exactly cancelling out sublattice magnetisation |
| C. | randomly oriented |
| D. | all aligned antiparallel such that the sublattice cancels out exactly |
| Answer» C. randomly oriented | |
| 505. |
If Vr is the reverse voltage across a graded P-N Junction, then the junction capacitance cj is proportional to |
| A. | (Vr)2 |
| B. | (Vr)n |
| C. | (Vr)-n |
| D. | (Vr)3/2 |
| Answer» C. (Vr)-n | |
| 506. |
In an n type semiconductor |
| A. | number of free electrons and holes are equal |
| B. | number of free electrons is much greater than the number of holes |
| C. | number of free electrons may be equal or less than the number of holes |
| D. | number of holes is greater than the number of free electrons |
| Answer» C. number of free electrons may be equal or less than the number of holes | |
| 507. |
If ib is plate current, eb is plate voltage and ec is grid voltage the v-i curve of a vacuum triode is ib = 0.003 (eb + kec)n. Typical values of k and n are |
| A. | 0.5 and 1 |
| B. | - 2 and 1 |
| C. | 30 and 1 |
| D. | 30 and 1.5 |
| Answer» E. | |
| 508. |
Dielectric strength of which of the following material has the highest dielectric strength? |
| A. | Porcelain |
| B. | Soft rubber |
| C. | Glass |
| D. | Joule effect |
| Answer» E. | |
| 509. |
In a 741 OP-amp, there is 20 dB/decade fall-off starting at a relatively low frequency. This is due to |
| A. | applied load |
| B. | internal compensation |
| C. | impedance of the source |
| D. | power dissipation in the chip |
| Answer» E. | |
| 510. |
For a P-N junction diode, the current in reverse bias may be |
| A. | few amperes |
| B. | between 0.5 A and 1 A |
| C. | few milliamperes |
| D. | few micro or nanoamperes |
| Answer» E. | |
| 511. |
The ripple factor for a bridge rectifier is |
| A. | 0.406 |
| B. | 1.21 |
| C. | 1.11 |
| D. | 2.22 |
| Answer» C. 1.11 | |
| 512. |
The electric breakdown strength is affected by |
| A. | shape of the waveform of applied voltage |
| B. | steepness of the wavefront of the applied voltage |
| C. | composition of the material |
| D. | all of the above |
| Answer» E. | |
| 513. |
A good ohmic contact on a P-type semiconductor chip is formed by introducing |
| A. | gold as an impurity below the contact |
| B. | high concentration of donors below the contact |
| C. | high concentration of acceptors below the contact |
| D. | thin insulator layer between the metal and semiconductor |
| Answer» C. high concentration of acceptors below the contact | |
| 514. |
The merging of a hole and an electron is called |
| A. | recombination |
| B. | covalent bonding |
| C. | thermal union |
| D. | none of the above |
| Answer» B. covalent bonding | |
| 515. |
In a transistor operating in forward active mode |
| A. | depletion layer between emitter and base is thin and that between base and collector is also thin |
| B. | both depletion regions are thick |
| C. | depletion layer between emitter and base is thin and that between base and collector is thick |
| D. | depletion layer between emitter and base is thick and that between base and collector is thin |
| Answer» D. depletion layer between emitter and base is thick and that between base and collector is thin | |
| 516. |
The voltage across the secondary of the transformer in a half wave rectifier with a shunt capacitor filter is 50 volts. The maximum voltage that will occur on the reverse biased diode will be |
| A. | 100 V |
| B. | 88 V |
| C. | 50 V |
| D. | 25 V |
| Answer» B. 88 V | |
| 517. |
In an integrated circuit the SiO2 layers provide |
| A. | electrical connection to external Ckt. |
| B. | physical strength |
| C. | isolation |
| D. | conducting path. |
| Answer» D. conducting path. | |
| 518. |
In a bipolar transistor, the emitter base junction has |
| A. | forward bias |
| B. | reverse bias |
| C. | zero bias |
| D. | zero or reverse bias |
| Answer» B. reverse bias | |
| 519. |
The Hall constant in Si bar is given by 5 x 103 cm3/ coulomb, the hole concentration in the bar is given by |
| A. | 105/cm3 |
| B. | 1.25 x 1015/cm3 |
| C. | 1.5 x 1015/cm3 |
| D. | 1.6 x 1015/cm3 |
| Answer» C. 1.5 x 1015/cm3 | |
| 520. |
Secondary emission results |
| A. | when temperature of metals is raised to a level above the crystallization temperature |
| B. | when metals are subjected to strong magnetic fields |
| C. | when light rays fall on the metal surface |
| D. | when a high velocity beam of electrons strikes as metal surface |
| Answer» C. when light rays fall on the metal surface | |
| 521. |
At 0 K the forbidden energy gap in intrinsic semi conductor is about |
| A. | 10 eV |
| B. | 6 eV |
| C. | 1 eV |
| D. | 0.2 eV |
| Answer» D. 0.2 eV | |
| 522. |
Consider the following statement: At finite temperature, magnetic dipoles in a material are randomly oriented giving low magnetization. When magnetic field H is applied, the magnetization? Increases with HDecreases with HDecreases with temp for constant H Which of the statement given above is/are correct? |
| A. | 1 |
| B. | 2 |
| C. | 2, 3 |
| D. | 1 and 3 |
| Answer» E. | |
| 523. |
The light output of LED varies as (current)n. The value of n is about |
| A. | 0.5 |
| B. | 1 |
| C. | 1.3 |
| D. | 2.1 |
| Answer» D. 2.1 | |
| 524. |
Which of the following elements act as donor impurities? GoldPhosphorusBoronAntimonyArsenicIndium Select the answer using the following codes : |
| A. | 1, 2 and 3 |
| B. | 1, 2, 4, and 6 |
| C. | 3, 4, 5 and 6 |
| D. | 2, 4 and 5 |
| Answer» E. | |
| 525. |
Introducing a resistor in the emitter of a common amplifier stabilizes the d.c. operating point against variations in |
| A. | only the temperature |
| B. | only β of the transistor |
| C. | both temperature and β |
| D. | none of these |
| Answer» D. none of these | |
| 526. |
In a reverse biased P-N junction, the current through the junction increases abruptly at |
| A. | zero voltage |
| B. | 1.2 V |
| C. | 0.72 V |
| D. | breakdown voltage |
| Answer» E. | |
| 527. |
The v-i characteristics of a diode may be linear or non linear. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 528. |
A reverse voltage of 18 V is applied to a semiconductor diode. The voltage across the depletion layer is |
| A. | 0 V |
| B. | 0.7 V |
| C. | about 10 V |
| D. | 18 V |
| Answer» E. | |
| 529. |
In the saturation region of CE output characteristics of n-p-n transistor, VCE is about |
| A. | 0.5 V |
| B. | 15 V |
| C. | - 0.5 V |
| D. | - 15 V |
| Answer» B. 15 V | |
| 530. |
Two identical silicon diodes D1 and D2 are connected back to back shown in figure. The reverse saturation current Is of each diode is 10-8 amps and the breakdown voltage VBr is 50 v. Evaluate the voltages VD1 and VD2 dropped across the diodes D1 and D2 assuming KT/q to be 25 m V. |
| A. | 4.983 V, 0.017 V |
| B. | - 4.98 V, - 0.017 V |
| C. | 0.17 V, 4.983 V |
| D. | - 0.017 V, - 4.98 V |
| Answer» C. 0.17 V, 4.983 V | |
| 531. |
A thermistor is a |
| A. | thermocouple |
| B. | thermometer |
| C. | miniature resistance |
| D. | heat sensitive explosive |
| Answer» D. heat sensitive explosive | |
| 532. |
In a JFET avalanche breakdown occurs when VDS = 22 V and VGS = 0. If VGS = -1 V, the avalanche breakdown will occur at |
| A. | VDS = 22 V |
| B. | VDS more than 22 V |
| C. | VDS equal to or more than 22 V |
| D. | VDS less than 22 V |
| Answer» E. | |
| 533. |
Which of these has degenerate p and n materials? |
| A. | Zener diode |
| B. | PIN diode |
| C. | Tunnel diode |
| D. | Photo diode |
| Answer» D. Photo diode | |
| 534. |
EG for silicon is 1.12 eV and that for germanium is 0.72 eV. Therefore it can be concluded that |
| A. | more number of electron-hole pairs will be generated in silicon than in germanium at room temperature |
| B. | less number of electron hole pairs will be generated in silicon than in germanium at room temperature |
| C. | equal number of electron-hole pairs will be generated in both at lower temperatures |
| D. | equal number of electron-hole pairs will be generated in both at higher temperatures |
| Answer» C. equal number of electron-hole pairs will be generated in both at lower temperatures | |
| 535. |
When a p-n junction is forward biased, the current remains zero till the applied voltage overcomes the barrier potential. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 536. |
In energy band diagram of p type semiconductor the acceptor energy level is |
| A. | in valence band |
| B. | in conduction band |
| C. | slightly above valence band |
| D. | slightly below conduction band |
| Answer» D. slightly below conduction band | |
| 537. |
The function off an oxide layer in an IC device is to mask against diffusion or ion implantationinsulate the surface electricallyincrease the melting point of Siproduce a chemically stable protective layer |
| A. | 1, 2, 3 |
| B. | 1, 3, 4 |
| C. | 2, 3, 4 |
| D. | 4, 1, 2 |
| Answer» E. | |
| 538. |
For a BJT, under the saturation condition, |
| A. | IC = βIB |
| B. | IC = aIB |
| C. | IC is independent of all other parameters |
| D. | IC < βIB |
| Answer» E. | |
| 539. |
When an electron rises through a potential of 100 V it will acquired an energy of |
| A. | 100 eV |
| B. | 100 Joules |
| C. | 100 ergs |
| D. | 100 x 10-6 Newtons |
| Answer» B. 100 Joules | |
| 540. |
When a semiconductor bar is heated at one end, a voltage across the bar is developed. If the heated is positive the semiconductor is |
| A. | P-type |
| B. | n-type |
| C. | intrinsic |
| D. | highly degenerate |
| Answer» E. | |
| 541. |
The atomic number of silicon is 14. It can be therefore concluded that |
| A. | a silicon atom contains 14 protons |
| B. | a silicon atom contains 14 neutrons |
| C. | a silicon atom contains 14 electrons |
| D. | all of the above |
| Answer» E. | |
| 542. |
The current due to thermionic emission is proportional to |
| A. | T |
| B. | T2 |
| C. | T3 |
| D. | T4 |
| Answer» C. T3 | |
| 543. |
Tuned voltage amplifiers are not used |
| A. | radio receivers |
| B. | public address system |
| C. | T.V. Receivers |
| D. | band of freq. selected and amplified |
| Answer» C. T.V. Receivers | |
| 544. |
For a junction FET in the pinch off region, as the drain voltage is increased, the drain current |
| A. | becomes zero |
| B. | abruptly decrease |
| C. | abruptly increases |
| D. | remains constant |
| Answer» E. | |
| 545. |
The relation between plate current and plate voltage of a vacuum diode is called |
| A. | Richardson Dushman equation |
| B. | Langmuir Child law |
| C. | Ohm's law |
| D. | Boltzmann's law |
| Answer» C. Ohm's law | |
| 546. |
In the figure shows the circuits symbol of |
| A. | FET |
| B. | PMOSFET |
| C. | CMOSFET |
| D. | NMOSFET |
| Answer» E. | |
| 547. |
The holes diffuse from P-region to the N-region in a P-N junction diode because |
| A. | there is greater concentration of holes in the P-region as compared to N-region |
| B. | there is greater concentration of holes in the N-region as compared to P-region |
| C. | the free electrons in the N-region attract them |
| D. | potential difference facilities such transfer |
| Answer» B. there is greater concentration of holes in the N-region as compared to P-region | |
| 548. |
The diffusion current is proportional to |
| A. | applied electric field |
| B. | concentration gradient of charge carrier |
| C. | square of the electric field |
| D. | cube of the applied electric field |
| Answer» C. square of the electric field | |
| 549. |
The dipole moment per unit volume as a function of E in the case of an insulator is given by (symbols have the usual meaning). |
| A. | P = ε0E (εr - E) |
| B. | P = ε0E |
| C. | P = |
| D. | P = |
| Answer» B. P = Œµ0E | |
| 550. |
The addition of n type impurity to intrinsic material creates allowable energy levels. |
| A. | slightly below conduction band |
| B. | slightly above conduction band |
| C. | slightly below valence band |
| D. | slightly above valence band |
| Answer» B. slightly above conduction band | |