MCQOPTIONS
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MCQOPTIONS
This section includes 595 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.
| 351. |
A vacant electronic state moves in the same direction as would a positive charge carrier. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 352. |
Which of the following is used in lightning arresters? |
| A. | Thermistor |
| B. | Photoconductor |
| C. | Transistor |
| D. | Varistor |
| Answer» E. | |
| 353. |
The transition of electron from energy level W1 to W2 is associated with emission or absorption of electro magnetic radiation of frequency f such that |
| A. | hf = |W1 - W2| |
| B. | |W1 - W2|f = h |
| C. | hf = 0.5|W1 - W2| |
| D. | (hf)2 = |W1 - W2| |
| Answer» B. |W1 - W2|f = h | |
| 354. |
Dielectric constant of transformer oil is about |
| A. | 1 |
| B. | 4 |
| C. | 10 |
| D. | 20 |
| Answer» C. 10 | |
| 355. |
At room temperature the number of conducting electrons in an intrinsic semiconductor |
| A. | is almost equal to the number of valence electrons |
| B. | is about half the number of valence electrons |
| C. | is small as compared to the number of valence electrons |
| D. | is a very small fraction of the number of valence electrons |
| Answer» E. | |
| 356. |
Assertion (A): Drift velocity of electrons is proportional to the applied electric field E.Reason (R): The average drift velocity per unit field is called 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 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 | |
| 357. |
In a specimen of silicon steel, a field strength of 200 A/m causes a flux density of 0.5 T. In a specimen of cast iron, the same H would cause B to be |
| A. | 0.5 T |
| B. | less than 0.5 T |
| C. | more than 0.5 T |
| D. | 0.5 T or more or less |
| Answer» C. more than 0.5 T | |
| 358. |
The class of insulation of impregnated paper is |
| A. | A |
| B. | B |
| C. | C |
| D. | F |
| Answer» B. B | |
| 359. |
High frequency inductors and capacitors are commonly plated with silver. The main purpose of this is to |
| A. | reduce dc resistance |
| B. | reduce ac resistance |
| C. | increase dc resistance |
| D. | increase ac resistance |
| Answer» C. increase dc resistance | |
| 360. |
In ferromagnetic materials, the orientation between neighbouring permanent dipoles is parallel. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 361. |
The number of valence electrons in trivalent impurity is |
| A. | 5 |
| B. | 4 |
| C. | 3 |
| D. | 1 |
| Answer» D. 1 | |
| 362. |
Assertion (A): Orbital magnetic moment of an electron in an atom is of the order of 1 Bohr magneton.Reason (R): 1 Bohr magneton = 9.27 x 10-24 A/m2. |
| 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 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 | |
| 363. |
A piece of iron is placed in a magnetic field |
| A. | the magnetic field will not be affected |
| B. | the magnetic lines of force will bend to pass through the piece |
| C. | the magnetic lines of force will bend away from the piece |
| D. | any of the above depending on type of iron |
| Answer» C. the magnetic lines of force will bend away from the piece | |
| 364. |
Assertion (A): The resistance of a copper specimen changes by about 22% when temperature is increased from room temperature to 700°C.Reason (R): The physical properties of a material are determined mostly by the extent of impurities. |
| 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 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 | |
| 365. |
Electrical conductivity of metals expressed in ohm-1 m-1 is of the order of |
| A. | 1010 |
| B. | 105 |
| C. | 43565 |
| D. | 43626 |
| Answer» C. 43565 | |
| 366. |
If B, H and M denote flux density, field intensity and magnetisation, B = μ0 (H + M). |
| A. | 1 |
| B. | |
| Answer» B. | |
| 367. |
Which solid dielectric has highest temperature limit? |
| A. | E |
| B. | H |
| C. | C |
| D. | F |
| Answer» D. F | |
| 368. |
An atom of a rare gas is placed is an electric field E. Then |
| A. | the nucleus will be shifted in the direction of E by an amount which is proportional to E. |
| B. | the nucleus will not be shifted. |
| C. | the nucleus will be shifted in the direction of E by an amount which is independent of E. |
| D. | the nucleus will be shifted in a direction opposite to that of E. |
| Answer» B. the nucleus will not be shifted. | |
| 369. |
Which inductor is used at high frequencies? |
| A. | Cast iron cored |
| B. | Sheet steel cored |
| C. | Iron alloy cored |
| D. | Ceramic cored |
| Answer» E. | |
| 370. |
In an intrinsic semiconductor, at a given temperature T |
| A. | the number of electrons-hole pairs generated per second due to thermal motion are equal to the number of electron-hole pairs lost per second due to recombination |
| B. | the number of electron-hole pairs generated per second due to thermal motion is always less than the number of electron-hole pairs lost per second due to recombination |
| C. | the number of electron hole pairs generated per second due to thermal motion is always more than the number of electron-hole pairs lost per second due to recombination |
| D. | any of the above |
| Answer» B. the number of electron-hole pairs generated per second due to thermal motion is always less than the number of electron-hole pairs lost per second due to recombination | |
| 371. |
Assertion (A): Silicon is the most favoured semiconductor material.Reason (R): PIV for silicon diode is more than that for germanium diode. |
| 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 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 | |
| 372. |
A sheet of bakelite is inserted between the plates of an air capacitor. The capacitance will |
| A. | increase |
| B. | decrease |
| C. | remain the same |
| D. | may increase or decrease |
| Answer» B. decrease | |
| 373. |
A circular sphere mile is the area of cross-section of a wire |
| A. | having a diameter equal to 1 miles |
| B. | having a radius equal to 1 miles |
| C. | having a circumference equal to 1 miles |
| D. | none of the above |
| Answer» B. having a radius equal to 1 miles | |
| 374. |
For a core having a relative permeability μr, magnetic dipole moment per unit volume M and field strength H, the flux density B is |
| A. | B = μr (H + M) |
| B. | B = μ0 (H + M) |
| C. | B = μ0μr (H + M) |
| D. | B = μ0μr (H - M) |
| Answer» C. B = Œº0Œºr (H + M) | |
| 375. |
Macroscopic quantities of a given material |
| A. | are absolutely constant |
| B. | are a function of temperature |
| C. | are a function of temperature, pressure field |
| D. | none of the above |
| Answer» E. | |
| 376. |
Assertion (A): The regular or irregular stacking of atoms has importanteffect on properties of materials.Reason (R): The arrangement of atoms in a given material can be studied using X-rays. |
| 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 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 | |
| 377. |
Even at room temperature, an intrinsic semiconductor has some holes. These holes are due to |
| A. | electron |
| B. | doping |
| C. | thermal energy |
| D. | free electrons |
| Answer» D. free electrons | |
| 378. |
A dielectric material must be |
| A. | insulator |
| B. | good conductor |
| C. | resistor |
| D. | semiconductor |
| Answer» B. good conductor | |
| 379. |
The magnetic moment in units of Bohr magneton of a ferrous ion in any ferrite is |
| A. | zero |
| B. | 2 |
| C. | 4 |
| D. | 6 |
| Answer» D. 6 | |
| 380. |
Assertion (A): For elemental dielectrics, P = NaeEi where N is number of atoms/m3, P is polarization, ae is electronic polarization and Ei is internal electric field.Reason (R): In elemental dielectrics there are no permanent dipoles or ions. |
| 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 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 correct explanation of A | |
| 381. |
An air cored inductance is a |
| A. | linear circuit element because its reactance varies linearly with voltage at a fixed frequency |
| B. | linear circuit element because its current varies linearly with voltage at a fixed frequency |
| C. | nonlinear circuit element due to saturation of core |
| D. | nonlinear circuit element because v = |
| Answer» B. linear circuit element because its current varies linearly with voltage at a fixed frequency | |
| 382. |
Wood is a diamagnetic material. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 383. |
In a metal the probability of a state 0.1 eV below Fermi level being occupied |
| A. | is more than the probability of state 0.1 eV above Fermi level being occupied |
| B. | is the same as the probability of state 0.1 eV above Fermi level being occupied |
| C. | is less than the probability of state 0.1 eV above Fermi level being occupied |
| D. | may be equal to or more or less than the probability of state 0.1 eV above Fermi level being occupied |
| Answer» B. is the same as the probability of state 0.1 eV above Fermi level being occupied | |
| 384. |
Assertion (A): Relative permittivity is determined by the atomic structure of the material.Reason (R): Absolute permittivity is determined by the atomic structure of the material. |
| 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 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 | |
| 385. |
Bitter powder patterns prove the existence of domains. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 386. |
The phenomenon of dielectric hysteresis occurs with |
| A. | dc |
| B. | ac |
| C. | both ac and dc |
| D. | none of the above |
| Answer» C. both ac and dc | |
| 387. |
Assertion (A): Magnetic susceptibility of copper is -0.5 x 10-5.Reason (R): Copper is diamagnetic material. |
| 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 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 correct explanation of A | |
| 388. |
The residual resistivity of a binary alloy at 0 K is |
| A. | sum of residual resistivities of component metals |
| B. | difference of residual resistivities of component metals |
| C. | product of residual resistivities of component metals |
| D. | dependent on the concentration of minor component in the alloy |
| Answer» E. | |
| 389. |
A specimen of metal has n valence electrons per m3. If vx is the average velocity of these electrons, each having a charge e, the current density J is |
| A. | J = ne vx |
| B. | J = - ne vx |
| C. | J = |
| D. | J = |
| Answer» C. J = | |
| 390. |
Assertion (A): Ionic solids, in general, have no electrical conductivity.Reason (R): In ionic solids, electrons are tightly bound to the nucleus. |
| 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 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 correct explanation of A | |
| 391. |
An homogeneous dielectric material is subjected to an electric field E. If a small cavity is made inside the material, the electric field intensity inside and outside the cavity are different. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 392. |
The current flow in a semiconductor is due to |
| A. | holes |
| B. | electrons |
| C. | holes and electrons |
| D. | holes, electrons and ions |
| Answer» D. holes, electrons and ions | |
| 393. |
n type semiconductors |
| A. | are negatively charged |
| B. | are produced when indium as impurity is added to germanium |
| C. | are produced phosphorus as impurity is added to silicon |
| D. | none of the above |
| Answer» D. none of the above | |
| 394. |
If a small amount of Cu is added to Ni conductor, then |
| A. | resistivity of Ni will decrease at all temperatures because Cu is a better conductor than Ni |
| B. | residual resistivity of Ni at low temperature will increase as Cu atoms act as defect centres |
| C. | resistivity of Ni will increase at all temperatures as Cu destroys the periodicity of Ni and acts as defects |
| D. | resistivity of Ni remains the same |
| Answer» D. resistivity of Ni remains the same | |
| 395. |
The number of valence electrons in silicon atom is |
| A. | 4 |
| B. | 2 |
| C. | 1 |
| D. | zero |
| Answer» B. 2 | |
| 396. |
Assertion (A): In some materials, ‚ààr is independent of temperature while in others, ‚ààr depends on temperature.Reason (R): If permanent dipoles are absent, ‚ààr varies with temperature. |
| 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 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 | |
| 397. |
If the radius of electron cloud around the nucleus of a rare gas atom is R, the electronic polarizability of the atom is porportional to |
| A. | R |
| B. | R2 |
| C. | R3 |
| Answer» D. | |
| 398. |
In a piezoelectric crystal, the application of mechanical force will cause |
| A. | plastic deformation of crystal |
| B. | magnetic dipoles in the crystal |
| C. | electrical polarization in the crystal |
| D. | shift in Fermi level |
| Answer» C. electrical polarization in the crystal | |
| 399. |
To produce magnetic flux, mmf is necessary. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 400. |
Assertion (A): For a dielectric, P = ‚àà0(‚ààr - 1) E.Reason (R): Dipole moment per unit volume is called polarization of dielectric. |
| 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 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 | |