MCQOPTIONS
Saved Bookmarks
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.
| 551. |
Assertion (A): For a solenoid having N turns, .Reason (R): For all magnetic materials, B increases linearly with I. |
| 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 | |
| 552. |
The unit for mmf is |
| A. | A |
| B. | Wb |
| C. | T |
| D. | V |
| Answer» B. Wb | |
| 553. |
In a homogeneous magnetic field H of a solenoid, the core carries a magnetic dipole moment M per unit volume equal to |
| A. | μ0 H |
| B. | μr H |
| C. | (μr - 1) H |
| D. | μoμr H |
| Answer» D. ŒºoŒºr H | |
| 554. |
A dielectric of relative permittivity ‚ààr is subjected to a homogeneous electric field E. The dipole moment P per unit volume is given by |
| A. | P = constant |
| B. | P = ‚àà0 E |
| C. | P = ‚àà0(‚ààr - 1) E |
| D. | P = ‚ààr E |
| Answer» D. P = ‚ààr E | |
| 555. |
If t is relaxation time and tc is average time between collisions, then in an isotropic metal |
| A. | t = tc |
| B. | t < tc |
| C. | tc < t |
| D. | T = 0.01 te |
| Answer» B. t < tc | |
| 556. |
The maximum temperature limit of class B insulation is |
| A. | 90°C |
| B. | 105°C |
| C. | 120°C |
| D. | 130°C |
| Answer» E. | |
| 557. |
Resistivity of rubber is about |
| A. | 102 Ω-m |
| B. | 10-2 Ω-m |
| C. | 5 x 108 Ω m |
| D. | 5 x 1012 Ω-m |
| Answer» E. | |
| 558. |
In carbon resistor colour code, the third band is red. It indicates |
| A. | two zeros |
| B. | three zeros |
| C. | multiplier is 0.01 |
| D. | multiplier is 0.1 |
| Answer» B. three zeros | |
| 559. |
For magnetic shielding, we need a ferromagnetic material. |
| A. | 1 |
| B. | |
| C. | Both A and R are true and R is correct explanation of A |
| D. | Both A and R are true but R is not correct explanation of A |
| Answer» B. | |
| 560. |
In intrinsic semiconductors, the number of free electrons is equal to the number of mobile holes. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 561. |
Tesla is a unit of |
| A. | flux |
| B. | field strength |
| C. | flux density |
| D. | MMF |
| Answer» D. MMF | |
| 562. |
When an electric field E is applied to solid and liquid insulating materials, the internal field Ei acting at the location of atom is such that |
| A. | Ei = E |
| B. | Ei > E |
| C. | Ei < E |
| D. | Ei may be equal to or less than E |
| Answer» C. Ei < E | |
| 563. |
Assertion (A): Electron concentration n, hole concentration p and charge concentration ni are related by ni2 = np.Reason (R): p type semiconductor is obtained by adding trivalent impurity to intrinsic semiconductor. |
| 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 | |
| 564. |
If a capacitor C having selectivity factor Q is scaled down in all its dimensions by a factor K without any altering the dielectric material, the new capacitor will have capacitance and selectivity as |
| A. | C, |
| B. | , Q |
| C. | , |
| D. | C, K |
| Answer» C. , | |
| 565. |
The chemical properties of atoms are determined by all the electrons and their configuration. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 566. |
Assertion (A): Silicon is less sensitive to changes in temperature than germanium.Reason (R): Cut in voltage in silicon is less than that in germanium. |
| 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 | |
| 567. |
Assertion (A): The angular momentum of an atom is due to three contributions viz. orbital, electron spin and nuclear spin.Reason (R): The nuclear spin magnetic moment is much more than electron spin magnetic moment. |
| 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 | |
| 568. |
The quantum numbers associated with electron motion are designed as |
| A. | a, b, c |
| B. | h, k, l |
| C. | n, m, l |
| D. | h, n, l |
| Answer» D. h, n, l | |
| 569. |
M = (μr - 1)H. |
| A. | 1 |
| B. | |
| C. | second column of periodic table |
| D. | third column of periodic table |
| Answer» B. | |
| 570. |
Assertion (A): Resistivity of a perfect single crystal of a metal goes to zero as T approaches zero.Reason (R): Scattering of electrons is due to deviations from perfect periodicity of lattice. |
| 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 | |
| 571. |
Some typical examples of macroscopic quantities are |
| A. | conductivity |
| B. | µr |
| C. | dielectric constant |
| D. | all of the above |
| Answer» E. | |
| 572. |
For a given value (n) of principle quantum number, the number of possible electronic states are |
| A. | n |
| B. | n2 |
| C. | n3 |
| D. | n |
| Answer» C. n3 | |
| 573. |
Assertion (A): Relaxation time and mean time between collisions are equal when scattering is isotropic.Reason (R): Mean free path of an electron λ, velocity of electron v and mean time between collisions tc are related as λ = vTc. |
| 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 | |
| 574. |
A vacuum parallel plate capacitor is charged. The field between the plates is 2 x 104 V/m. If the space between the plates is filled with a material having ‚ààr = 10, then the value of field in the dielectric will be |
| A. | 2 x 103 V/m |
| B. | x 104 V/m |
| C. | 210 x 104 V/m |
| D. | 2 x 105 V/m |
| Answer» B. x 104 V/m | |
| 575. |
Assertion (A): Helium, Argon and Neon are gaseous at room temperature.Reason (R): The atoms in Helium, Argon and Neon are chemically extremely inactive. |
| 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 | |
| 576. |
The minority carrier life time and diffusion constant in a semiconducting material are 100 μs and 100 cm2/s respectively. The diffusion length of carriers is |
| A. | 0.1 cm |
| B. | 0.01 cm |
| C. | 0.0141 cm |
| D. | 1 cm |
| Answer» B. 0.01 cm | |
| 577. |
If n denotes principal quantum number, the angular quantum number l = 0, 1... (n - 1). |
| A. | 1 |
| B. | |
| C. | Both A and R are true and R is correct explanation of A |
| D. | Both A and R are true but R is not correct explanation of A |
| Answer» B. | |
| 578. |
At a very low temperature, a semiconductor |
| A. | becomes a conductor |
| B. | becomes an insulator |
| C. | may become a conductor or an insulator |
| D. | will remain a semiconductor becomes a conductor or an insulator |
| Answer» C. may become a conductor or an insulator | |
| 579. |
Assertion (A): Atomic number of sodium is 11.Reason (R): Sodium has a body centred cubic lattice. |
| 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 | |
| 580. |
A parallel plate capacitor has its length, width and separation doubled. It fringing effects are neglected, to keep the capacitance same, the dielectric constant must be |
| A. | halved |
| B. | kept the same |
| C. | doubled |
| D. | made 4 times |
| Answer» B. kept the same | |
| 581. |
Assertion (A): Intrinsic resistivity of silicon is lower than that of germanium.Reason (R): Magnitude of free electron concentration in germanium is more than that of silicon. |
| 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» E. | |
| 582. |
Assertion (A): At a temperature of 1000 K, thermionic emission current is about 0.1 A/cm2 of surface.Reason (R): Thermionic emission current is given by Ith = SA0 T2 e-Ew/kT. |
| 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 | |
| 583. |
In paramagnetic materials |
| A. | permanent magnetic dipoles exist but the interaction between neighbouring dipoles is negligible |
| B. | permanent magnetic dipole do not exist |
| C. | permanent magnetic dipoles exist and the interaction between neighbouring dipoles is very strong |
| D. | permanent magnetic dipole moment may or may not exist |
| Answer» B. permanent magnetic dipole do not exist | |
| 584. |
Above ferroelectric curie temperature, spontaneous polarization in ferroelectric materials becomes stronger. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 585. |
If a piece of wood is placed in a magnetic field |
| A. | the magnetic field will not be affected |
| B. | the magnetic lines of force will bend towards the piece |
| C. | the magnetic lines of force will bend away from the piece |
| D. | the flux may increase or decrease |
| Answer» B. the magnetic lines of force will bend towards the piece | |
| 586. |
The dielectric losses do not depend on frequency. |
| A. | 1 |
| B. | |
| C. | Both A and R are true and R is correct explanation of A |
| D. | Both A and R are true but R is not correct explanation of A |
| Answer» C. Both A and R are true and R is correct explanation of A | |
| 587. |
In crystalline solids, atoms are stacked in a regular manner. |
| A. | 1 |
| B. | |
| C. | Weiss temperature |
| D. | Curie temperature |
| Answer» B. | |
| 588. |
For a paramagnetic material, susceptiblity increases with increasing temperature. |
| A. | 1 |
| B. | |
| C. | large size transformers |
| D. | MCB |
| Answer» C. large size transformers | |
| 589. |
The temperature at which some materials become superconductors is called |
| A. | Transition temperature |
| B. | Curie temperature |
| C. | Neel temperature |
| D. | Onnes temperature |
| Answer» B. Curie temperature | |
| 590. |
Assertion (A): Diamond and carborudum are both very hard materials.Reason (R): Valence band can be extremely strong. |
| 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 | |
| 591. |
The conductivity of intrinsic semiconductor is given by |
| A. | eni(μp - μn) |
| B. | eni(μp + μn) |
| C. | ni(μp + μn) |
| D. | ni(μpμn) |
| Answer» C. ni(Œºp + Œºn) | |
| 592. |
The attraction between the nucleus and valence electron of copper atom is |
| A. | zero |
| B. | weak |
| C. | strong |
| D. | either zero or strong |
| Answer» C. strong | |
| 593. |
When an electron moves at velocity v in combined electric and magnetic fields E and H, the Lorentz force F is F = - e(E + v x B). |
| A. | 1 |
| B. | |
| Answer» B. | |
| 594. |
The number of protons in a silicon atom are |
| A. | 4 |
| B. | 8 |
| C. | 12 |
| D. | 14 |
| Answer» E. | |
| 595. |
Which element exhibits the property of inertia? |
| A. | Resistance |
| B. | Capacitance |
| C. | Inductance |
| D. | Both resistance and inductance |
| Answer» D. Both resistance and inductance | |