MCQOPTIONS
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MCQOPTIONS
This section includes 9294 Mcqs, each offering curated multiple-choice questions to sharpen your Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 7451. |
Resistivity of metals consists of two parts, one part constant and the other temperature dependent. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7452. |
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. | |
| 7453. |
As per temperature limits, the number of categories of solid dielectrics are |
| A. | 7 |
| B. | 6 |
| C. | 8 |
| D. | 5 |
| Answer» B. 6 | |
| 7454. |
By inserting a plate of dielectric between the plates of a parallel plate capacitor, the energy stored in the capacitor is increased five times. The dielectric constant of material is |
| A. | <img src="/_files/images/electronics-and-communication-engineering/materials-and-components/235-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/materials-and-components/235-2.png"> |
| C. | 5 |
| D. | 25 |
| Answer» D. 25 | |
| 7455. |
Schrodinger wave equation is a |
| A. | linear equation |
| B. | differential equation |
| C. | partial differential equation |
| D. | none of the above |
| Answer» D. none of the above | |
| 7456. |
In solid insulator materials having only one kind of atom, the types of polarization which exist are |
| A. | electronic only |
| B. | electronic and ionic |
| C. | electronic, ionic and permanent |
| D. | electronic and permanent |
| Answer» B. electronic and ionic | |
| 7457. |
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 | |
| 7458. |
Silicon and germanium have diamond structure. The number of atoms in a volume equal to a3 where a is the edge of elementary cube are |
| A. | 32 |
| B. | 16 |
| C. | 8 |
| D. | 4 |
| Answer» D. 4 | |
| 7459. |
If B, H and M denote flux density, field intensity and magnetisation, B = 0 (H + M). |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7460. |
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 | |
| 7461. |
A capacitor can be represented by a capacitance and resistance in parallel. For a good capacitor, this parallel resistance should be |
| A. | negligible |
| B. | low |
| C. | high |
| D. | very high |
| Answer» E. | |
| 7462. |
The number of protons in germanium atom is |
| A. | 4 |
| B. | 16 |
| C. | 28 |
| D. | 32 |
| Answer» E. | |
| 7463. |
Sulphur hexafluoride is used in |
| A. | transformers |
| B. | generators |
| C. | relays |
| D. | circuit breakers |
| Answer» E. | |
| 7464. |
The number of valence electrons in trivalent impurity is |
| A. | 5 |
| B. | 4 |
| C. | 3 |
| D. | 1 |
| Answer» D. 1 | |
| 7465. |
The v-i characteristic shown in the given figure is for |
| A. | thermistor |
| B. | photoconductor |
| C. | varistor |
| D. | none of the above |
| Answer» D. none of the above | |
| 7466. |
The induced magnetic dipole moment has a direction opposite to the applied magnetic field. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7467. |
The number of valence electrons in silicon atom is |
| A. | 4 |
| B. | 2 |
| C. | 1 |
| D. | zero |
| Answer» B. 2 | |
| 7468. |
r is determined by the atomic structure of the dielectric. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7469. |
Two coaxial metallic cylinders have radii R1 and R2. The space between them is filled with a dielectric having dielectric constant r. The capacitance per metre length is |
| A. | <img src="/_files/images/electronics-and-communication-engineering/materials-and-components/63-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/materials-and-components/63-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/materials-and-components/63-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/materials-and-components/63-4.png"> |
| Answer» C. <img src="/_files/images/electronics-and-communication-engineering/materials-and-components/63-3.png"> | |
| 7470. |
The quantum numbers associated with electron motion are designed as |
| A. | <i>a, b, c </i> |
| B. | <i>h, k, l </i> |
| C. | <i>n, m, l</i> |
| D. | <i>h, n, l </i> |
| Answer» D. <i>h, n, l </i> | |
| 7471. |
The units for r are |
| A. | Farads |
| B. | Farads/m |
| C. | <img src="/_files/images/electronics-and-communication-engineering/materials-and-components/206-1.png"> |
| D. | no units |
| Answer» E. | |
| 7472. |
The carrier mobility in a semiconductor is 0.4 m2/Vs. Its diffusion constant at 300 K will be (in m2/s) |
| A. | 0.40 |
| B. | 0.16 |
| C. | 0.04 |
| D. | 0.01 |
| Answer» E. | |
| 7473. |
Which of these has lowest dielectric strength? |
| A. | Dry air |
| B. | Wet air |
| C. | Cotton |
| D. | Paper |
| Answer» C. Cotton | |
| 7474. |
Fleming's left hand rule is used to find |
| A. | direction of force on a current carrying conductor |
| B. | direction of flux in solenoid |
| C. | direction of magnetic field due to a current carrying conductor |
| D. | direction of induced emf |
| Answer» B. direction of flux in solenoid | |
| 7475. |
In the wave mechanical theory, the maximum of the charge distribution in the ground state occurs for a distance from the nucleus equal to |
| A. | first Bohr radius |
| B. | second Bohr radius |
| C. | third Bohr radius |
| D. | either first or second Bohr radius |
| Answer» B. second Bohr radius | |
| 7476. |
When Schrodinger equation is applied to the motion of electron in the field of protons, the physically acceptable solutions for the wave function exist for quantum number which are |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 5 |
| Answer» C. 4 | |
| 7477. |
For dielectrics in alternating field, polarizability ae is a complex quantity. The imaginary part of ae is zero for |
| A. | = 0 |
| B. | |
| C. | = 0 and |
| D. | = natural frequency |
| E. | <sub>0</sub> |
| Answer» D. = natural frequency | |
| 7478. |
Yettrium-iron garnet (Y2Fe5O12) is a soft magnetic material suitable for applications involving |
| A. | dc |
| B. | 50 Hz ac |
| C. | ac of a few K Hz |
| D. | ac of a few hundred MHz |
| Answer» B. 50 Hz ac | |
| 7479. |
The core of a solenoid is made of material of relative permeability r. A small cavity area dA and length dl is cut in the core. If it is desired that flux density in the cavity should be equal to B0 |
| A. | the fields inside and outside the cavity must be equal |
| B. | the field inside the cavity must be made stronger than field outside the cavity |
| C. | the field inside the cavity must be made weaker than the field outside the cavity |
| D. | none of the above |
| Answer» C. the field inside the cavity must be made weaker than the field outside the cavity | |
| 7480. |
A rare gas having N atoms/m3 is subjected to an electric field E. The electric dipole moment per unit volume is proportional to N and E. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7481. |
Ferrimagnetic materials have anti-parallel orientation of equal moments of permanent dipoles. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7482. |
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 | |
| 7483. |
If the number of atoms per unit volume of a monoatomic gas changes, the dielectric constant still remains constant. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7484. |
As the atoms of rare gases become larger, electronic polarizability |
| A. | increases |
| B. | decreases |
| C. | remains the same |
| D. | may increase or decrease |
| Answer» D. may increase or decrease | |
| 7485. |
When a material is in superconducting state and a magnetic field is applied |
| A. | the superconducting property is not affected |
| B. | the superconducting property may be affected and resistivity may increase from zero to a low value |
| C. | the superconducting property may be destroyed |
| D. | the material may become an insulator |
| Answer» D. the material may become an insulator | |
| 7486. |
For a diamagnetic material, r = 1. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7487. |
We can know the arrangement of atom in a material by studying electron diffraction pattern. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7488. |
Consider the following materials NickelSilverOxygenAluminium The correct sequence in the order of decreasing permeability is |
| A. | 1, 4, 3, 2 |
| B. | 1, 4, 2, 3 |
| C. | 4, 1, 3, 2 |
| D. | 4, 1, 2, 3 |
| Answer» C. 4, 1, 3, 2 | |
| 7489. |
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. | |
| 7490. |
A magnetic field exists around |
| A. | moving charges |
| B. | static charges |
| C. | iron |
| D. | copper |
| Answer» B. static charges | |
| 7491. |
The resistance of a photoconductor |
| A. | increases with increase in light intensity |
| B. | decreases with increase in light intensity |
| C. | may increase or decrease with increase in light intensity |
| D. | remains constant |
| Answer» C. may increase or decrease with increase in light intensity | |
| 7492. |
The magnetic quantum number determines the component of angular momentum along a prescribed direction. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7493. |
Wood is a diamagnetic material. |
| A. | True |
| B. | False |
| Answer» C. | |
| 7494. |
Curie Weiss law is . |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7495. |
With increase in temperature, the electrical conductivity would |
| A. | increase in metals as well as in intrinsic semiconductor |
| B. | increase in metals but decrease in intrinsic semiconductor |
| C. | decrease in metals but increase in intrinsic semiconductor |
| D. | decrease in metals as well as in intrinsic semiconductor |
| Answer» D. decrease in metals as well as in intrinsic semiconductor | |
| 7496. |
Assertion (A): If an atom of polarizability a is placed in homogeneous field E, the energy stored is 0.5 aE2.Reason (R): Capacitance of an isolated conducting sphere R in vacuum is 4 p 0 R farads. |
| 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 | |
| 7497. |
Which of the following are true for relative dielectric constant? It is dimensionless.It is equal to 1 for vacuum.It is equal to 1 for all substances. |
| A. | 1 and 2 only |
| B. | 2 and 3 only |
| C. | 1 and 3 only |
| D. | 1, 2 and 3 |
| Answer» B. 2 and 3 only | |
| 7498. |
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 | |
| 7499. |
An electron for which l = 0 has zero orbital magnetic dipole moment. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7500. |
Schrodinger wave equation is partial differential equation. |
| A. | True |
| B. | False |
| Answer» B. False | |