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.
| 401. |
An electron shell corresponding to principal quantum number n can contain a maximum of |
| A. | n2 electrons |
| B. | 2n2 electrons |
| C. | 2n electron |
| D. | n3 electron |
| Answer» C. 2n electron | |
| 402. |
For iron, the ferromagnetic Curie temperature is |
| A. | about 20 K |
| B. | about 100°C |
| C. | about -20°C |
| D. | about 1000 K |
| Answer» E. | |
| 403. |
A single layer air cored coil has n turns and inductance L. If a new coil is formed by having 2n turns while keeping the coil length and diameter the same, the new inductance is |
| A. | 0.5 L |
| B. | L |
| C. | 2 L |
| D. | 4 L |
| Answer» E. | |
| 404. |
If v is the velocity of electron, tc is the average time between collisions, the mean free path λ = vtc. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 405. |
For a superconductor, the relative permeability is |
| A. | zero |
| B. | high |
| C. | low |
| D. | either low or high |
| Answer» B. high | |
| 406. |
Rochelle salt is a ferroelectric material. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 407. |
A wire is carrying current I. The field intensity H at a distance r from the wire |
| A. | is directed towards wire |
| B. | is directed away from wire |
| C. | is tangential every where to a circle of radius r |
| D. | none of the above |
| Answer» D. none of the above | |
| 408. |
Consider the following statements An iron cored choke is non linear and passive device.A carbon resistor kept in sunlight is a time invariant and passive device.A dry cell is a time varying and active device.An air capacitor is time invariant and passive device. Of these statements |
| A. | 1, 2, 3 and 4 are correct |
| B. | 1, 2, 3 are correct |
| C. | 1, 2, 4 are correct |
| D. | 2 and 4 are correct |
| Answer» B. 1, 2, 3 are correct | |
| 409. |
In a rare gas, the molecules of some atoms have an excess positive or negative charge. The electric field tends to shift positive ions relative to negative ions. This is known as ionic polarization. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 410. |
Electrical contact materials used in switches, brushes, relay must possess |
| A. | high thermal conductivity and high melting point |
| B. | low thermal conductivity and low melting point |
| C. | high thermal conductivity and low melting point |
| D. | low thermal conductivity and high melting point |
| Answer» B. low thermal conductivity and low melting point | |
| 411. |
In body centred cubic structure, comers and centre of the cube are occupied by identical atoms. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 412. |
In a polyatomic gas, the types of polarization which exist together are |
| A. | electronic and orientational |
| B. | electronic and ionic |
| C. | ionic and orientational |
| D. | electronic, orientational and ionic |
| Answer» E. | |
| 413. |
Inductors used at V.H.F. are made using |
| A. | air core |
| B. | cast iron cored |
| C. | sheet steel cored |
| D. | thin film technique |
| Answer» E. | |
| 414. |
If ∈r = ∈r' - j∈r" tan δ = . |
| A. | 1 |
| B. | |
| Answer» B. | |
| 415. |
All magnetic materials exhibit the phenomenon of saturation. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 416. |
The colour code on a carbon resistor is brown-black-red-gold. The value of resistance is |
| A. | 100 Ω |
| B. | 1000 Ω |
| C. | 1000 Ω ± 5% |
| D. | 1000 Ω ± 10% |
| Answer» D. 1000 Œ© ¬± 10% | |
| 417. |
Schrodinger wave equation is partial differential equation. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 418. |
Assertion (A): In Figure, the intercept of the line on y-axis is equal to N (ae + ai), where N is number of atoms/m3, ae is electronic polarizability and ai is ionic polarizability.Reason (R): ae and ai are independent of 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» B. Both A and R are true but R is not correct explanation of A | |
| 419. |
Which of these has the highest dielectric strength? |
| A. | Mica |
| B. | Air |
| C. | Cotton |
| D. | Rubber |
| Answer» B. Air | |
| 420. |
Dielectric constant, under the condition of alternating fields, is a complex quantity. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 421. |
Hall effect is observed in a specimen (metal or semi- conductor) when it is carrying current and is placed in a magnetic field. The resultant electric field inside the specimen is |
| A. | normal to both current and magnetic field |
| B. | in the same direction as current |
| C. | in a direction anti parallel to magnetic field |
| D. | none of the above |
| Answer» B. in the same direction as current | |
| 422. |
The heat developed per m3 per second (W) in a conductor having a conductivity σ and a field E is |
| A. | W = σE2 |
| B. | W = σE |
| C. | W = |
| D. | W = (σE)0.5 |
| Answer» B. W = œÉE | |
| 423. |
In a specimen of ferromagnetic material, as the flux density is increased from zero to 2.5 T, µr will |
| A. | increase |
| B. | decrease |
| C. | first decrease then increase |
| D. | first increase then decrease |
| Answer» E. | |
| 424. |
In elemental dielectrics, the orientation and ionic polarization are absent. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 425. |
Antiferromagnetic materials do not have permanent dipoles. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 426. |
As the temperature of a pure silicon specimen is increased |
| A. | the number of free electrons increases |
| B. | the number of holes decreases |
| C. | the number of holes increases |
| D. | the number of free electrons and holes increases |
| Answer» E. | |
| 427. |
A conductor carries 10 A current in + x direction and is lying in a field having a flux density 0.2 T directed along + z direction. The magnitude of force per metre length and direction are |
| A. | 2 N, + y direction |
| B. | 2 N, - y direction |
| C. | 0.02 N, + y direction |
| D. | 0.02 N, - y direction |
| Answer» C. 0.02 N, + y direction | |
| 428. |
The two conductors of a transmission line carry equal current I in opposite direction. The force on each conductor is |
| A. | proportional to I |
| B. | proportional to I2 |
| C. | proportional to distance between the lines |
| D. | proportional to I3 |
| Answer» C. proportional to distance between the lines | |
| 429. |
‚ààr is determined by the atomic structure of the dielectric. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 430. |
Consider the following statementIf an electric field is applied to an n type semiconductor bar, the electrons and holes move in opposite directions due to their opposite charges. The net currents is both due to electrons and holes with electrons as majority carrierssum of hole and electron currentsdifference between electron and hole currents. Which of above statements are correct? |
| A. | 1 only |
| B. | 1 and 2 |
| C. | 2 only |
| D. | 3 only |
| Answer» C. 2 only | |
| 431. |
The orientation polarization is directly proportional to temperatureinversely proportional to temperatureinversely proportional to square of permanent dipole momentdirectly proportional to square of permanent dipole moment. Which of the above are correct? |
| A. | 1 and 3 only |
| B. | 2 and 3 only |
| C. | 1 and 4 only |
| D. | 2 and 4 only |
| Answer» E. | |
| 432. |
Magnetisation of a material is the magnetic dipole moment per m3. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 433. |
Which inductor is linear? |
| A. | Air cored |
| B. | Cast iron cored |
| C. | Sheet steel cored |
| D. | Iron alloy cored |
| Answer» B. Cast iron cored | |
| 434. |
The resistance of a superconductor is |
| A. | low |
| B. | very low |
| C. | very very low |
| D. | zero |
| Answer» E. | |
| 435. |
An electrolytic capacitor can be used for |
| A. | ac only |
| B. | dc only |
| C. | both ac and dc |
| D. | high frequency ac |
| Answer» C. both ac and dc | |
| 436. |
When a pentavalent impurity is added, the semiconductor becomes |
| A. | p type |
| B. | n type |
| C. | intrinsic |
| D. | neutral |
| Answer» C. intrinsic | |
| 437. |
A material which is lightly repelled by a magnetic field is known as |
| A. | diamagnetic material |
| B. | non-magnetic material |
| C. | ferromagnetic material |
| D. | paramagnetic material |
| Answer» B. non-magnetic material | |
| 438. |
Assertion (A): Both sodium and ferrous are ferromagnetic.Reason (R): Both sodium and ferrous have body centred cubic structure. |
| 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 | |
| 439. |
1 Bohr magneton = . |
| A. | 1 |
| B. | |
| Answer» B. | |
| 440. |
Assertion (A): In liquids and glassy substances, dielectric losses occur. Reason (R): The orientation polarization in many substances is frequency dependent. |
| 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 | |
| 441. |
For making a capacitor it is better to have a dielectric having |
| A. | high permittivity |
| B. | low permittivity |
| C. | permittivity same as that of air |
| D. | permittivity which is neither high nor low |
| Answer» B. low permittivity | |
| 442. |
The Ohm's law for conduction in metals is |
| A. | J = σE |
| B. | J = |
| C. | J ∝ σE |
| D. | J ‚àù |
| Answer» B. J = | |
| 443. |
The core of an atom consists of |
| A. | nucleus |
| B. | nucleus and all orbits |
| C. | nucleus and inner orbits |
| D. | none of the above |
| Answer» D. none of the above | |
| 444. |
Assertion (A): CO2 has no resultant dipole moment but CO has a dipole moment.Reason (R): The structure of CO2 is O = C = O. |
| 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 | |
| 445. |
Assertion (A): Doping level in extrinsic semiconductors is very small.Reason (R): Additional of impurity in the ratio of 1 part in 108 parts increases the number of charge carriers by about 20. |
| 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 | |
| 446. |
When two conductors carry currents in the same direction the force is repulsive. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 447. |
An electron is moving around a proton, in a circle of radius R. If flux density in the region is increased from zero to B, the force on the electron is |
| A. | |
| B. | eR (dB / dt) |
| Answer» B. eR (dB / dt) | |
| 448. |
If ∈r' and ∈r" are the real and imaginary parts of complex dielectric constant ∈r, and δ is the loss angle. Then |
| A. | |
| B. | |
| Answer» C. | |
| 449. |
In anti-ferromagnetic materials, the graph of susceptibility versus temperature shows a sharp maximum at a certain temperature. This temperature is known as |
| A. | Curie temperature |
| B. | Neel temperature |
| C. | Weiss temperature |
| D. | Bitter temperature |
| Answer» C. Weiss temperature | |
| 450. |
The number of tightly bound electrons in silicon atom are |
| A. | 14 |
| B. | 10 |
| C. | 6 |
| D. | 4 |
| Answer» C. 6 | |