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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.
| 7551. |
A piece of copper and another piece of Germanium are cooled from 30 C to 80 K. The resistance of |
| A. | copper decreases and germanium increases |
| B. | both decreases |
| C. | both increases |
| D. | copper increases and germanium decreases |
| Answer» B. both decreases | |
| 7552. |
The temperature coefficient of resistivity of semiconductors is |
| A. | positive |
| B. | negative |
| C. | may be positive or negative |
| D. | very low |
| Answer» C. may be positive or negative | |
| 7553. |
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 | |
| 7554. |
A parallel plate capacitor has area of plate A and plate separation d. Its capacitance is C. A metallic plate P of area A and negligible thickness is added as shown in Figure. The new value of capacitance is |
| A. | C |
| B. | 2C |
| C. | 0.5 C |
| D. | 0.25 C |
| Answer» B. 2C | |
| 7555. |
The wavelength of light emitted by GaAs laser is 8670 x 10-10 m. If h = 6.626 x 10-34 Js, velocity of light = 3 x 108 m/s and eV = 1.602 x 10-19 J, the energy gap in GaAs is |
| A. | 0.18 eV |
| B. | 0.7 eV |
| C. | 1.43 eV |
| D. | 2.39 eV |
| Answer» D. 2.39 eV | |
| 7556. |
Diamagnetic materials do not have permanent magnetic dipoles. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7557. |
Consider the following statement: In case of a superconductor B = 0 r is highdiamagnetism is hightransition temperature varies with isotopic mass. Of the above statements |
| A. | 1 and 2 are correct |
| B. | 2, 3, 4 are correct |
| C. | 1, 3, 4 are correct |
| D. | 2, 4 are correct |
| Answer» D. 2, 4 are correct | |
| 7558. |
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 | |
| 7559. |
When an atom of polarizability a is placed in an electric field E, the energy stored in atom is 0.5 a E2. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7560. |
When a dielectric material is subjected to alternating field, the absorption of energy by the material from the field is given by the imaginary part of polarizability. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7561. |
The merger of hole and free electron is called |
| A. | covalent bonding |
| B. | recombination |
| C. | thermal energy |
| D. | free electrons |
| Answer» C. thermal energy | |
| 7562. |
The induced magnetic dipole moment is independent of the permanent magnetic dipole moment. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7563. |
Carbon steel has a residual flux density of 1 Wb/m2. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7564. |
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 | |
| 7565. |
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 | |
| 7566. |
The number of protons in a copper atom are |
| A. | 2 |
| B. | 9 |
| C. | 11 |
| D. | 29 |
| Answer» E. | |
| 7567. |
The unit for mmf is |
| A. | A |
| B. | Wb |
| C. | T |
| D. | V |
| Answer» B. Wb | |
| 7568. |
The elements which become superconducting at extremely low temperatures are |
| A. | good conductors at room temperature |
| B. | ferromagnetic at room temperature |
| C. | relatively poor conductors at room temperature |
| D. | insulators at room temperature |
| Answer» D. insulators at room temperature | |
| 7569. |
A copper atom is neutral. Its core has a net charge of |
| A. | 0 |
| B. | + 1 |
| C. | - 1 |
| D. | + 2 |
| Answer» C. - 1 | |
| 7570. |
As the temperature of semiconductor is increased |
| A. | the average number of free charge carriers decreases |
| B. | the average number of free charge carriers increases |
| C. | the average number of free charge carriers remains the same |
| D. | the average number of free charge carriers may increase or decrease |
| Answer» C. the average number of free charge carriers remains the same | |
| 7571. |
The most important set of specifications of transformer oil include |
| A. | dielectric strength and viscosity |
| B. | dielectric strength and flash point |
| C. | viscosity and flash point |
| D. | flash point and viscosity |
| Answer» B. dielectric strength and flash point | |
| 7572. |
Nickel is a non-magnetic material. |
| A. | True |
| B. | False |
| Answer» C. | |
| 7573. |
If there are no permanent dipoles in a dielectric material, the dielectric constant is independent of temperature. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7574. |
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 | |
| 7575. |
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 | |
| 7576. |
The spin angular momentum along a given direction is either or . |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7577. |
The equation D = 0 r E refers only to isotropic materials. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7578. |
When a ferromagnetic substance is magnetised there are small changes in dimensions. This phenomenon is called |
| A. | hysteresis |
| B. | magnetostriction |
| C. | diamagnetism |
| D. | dipolar relaxation |
| Answer» C. diamagnetism | |
| 7579. |
Semiconductors have a positive temperature coefficient of resistivity. |
| A. | True |
| B. | False |
| Answer» C. | |
| 7580. |
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. | True |
| B. | False |
| Answer» C. | |
| 7581. |
Assertion (A): In some materials, r is independent of temperature while in others, r depends on temperature.Reason (R): If permanent dipoles are absent, r 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 | |
| 7582. |
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 | |
| 7583. |
Spontaneous polarization occurs in ferroelectric materials. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7584. |
Assertion (A): Relaxation time and mean time between collisions are equal when scattering is isotropic.Reason (R): Mean free path of an electron , velocity of electron v and mean time between collisions tc are related as = 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 | |
| 7585. |
An electron in a homogeneous magnetic field and having velocity perpendicular to the direction of field moves |
| A. | perpendicular to the field |
| B. | along the field |
| C. | along a straight line inclined at 45 to field |
| D. | in a circular path |
| Answer» E. | |
| 7586. |
Assertion (A): Copper is a monoatomic solid.Reason (R): In a metal the valence electrons belong to all atoms. |
| 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 | |
| 7587. |
The number of valence electrons in acceptor impurity are |
| A. | 5 |
| B. | 4 |
| C. | 3 |
| D. | 1 |
| Answer» D. 1 | |
| 7588. |
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 | |
| 7589. |
Semi conducting materials are all |
| A. | elements |
| B. | compounds |
| C. | elements or compounds |
| D. | elements or mixtures |
| Answer» D. elements or mixtures | |
| 7590. |
Silicon and germanium atoms combine orderly into array of atoms located in repetitive geometric pattern. This pattern is called |
| A. | crystal |
| B. | covalent bond |
| C. | molecule |
| D. | valence bond |
| Answer» B. covalent bond | |
| 7591. |
In a pure sample of silicon |
| A. | the number of holes and free electrons is always equal |
| B. | the number of free electrons is more than the number of holes |
| C. | the number of free electrons and holes is equal at low temperature |
| D. | the number of free electrons is less than number of holes |
| Answer» B. the number of free electrons is more than the number of holes | |
| 7592. |
Assertion (A): The optical dielectric constant (i.e., r at optical frequencies)of ionic dielectrics is less than static dielectric constant. Reason (R): At optical frequencies, Pi = 0. |
| 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 | |
| 7593. |
Assertion (A): Magnetism can be explained by the theory of magnetic domains.Reason (R): The existence of magnetic domains is evident from the Bitter powder patterns. |
| 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 | |
| 7594. |
Ferromagnetic materials |
| A. | shows spontaneous magnetisation below a certain temperature |
| B. | have resistivity very high as compared to that of iron |
| C. | can be used even at microwave frequencies |
| D. | all of the above |
| Answer» E. | |
| 7595. |
In a specimen of ferromagnetic material, as the flux density is increased from zero to 2.5 T, r will |
| A. | increase |
| B. | decrease |
| C. | first decrease then increase |
| D. | first increase then decrease |
| Answer» E. | |
| 7596. |
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 | |
| 7597. |
Assertion (A): If difference between static and optical dielectric constant is high, the mechanical compressiblity of that material is also high.Reason (R): For soft ions, ionic polarization per unit field is higher than that of hard 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 | |
| 7598. |
Rochelle salt is a ferroelectric material. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7599. |
Paramagnetic materials have permanent magnetic dipoles but interaction between neighbouring dipoles is negligible. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7600. |
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 | |