MATERIALS and COMPONENTS Questions and Answers :-
1. The dielectric losses do not depend on frequency.
2. 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
3. The rule that resistivity of conductors can be separated into two parts viz. temperature independent and temperature dependent is known as
A. Matthiessen’s rule
B. Debye rule
C. Curie rule
D. Onne’s rule
4. Above a certain temperature, the specific heat of a metal becomes constant. This temperature is called
A. Debye temperature
B. Curie temperature
C. Neel temperature
D. Transition temperature
5. A dielectric material must be
B. good conductor
6. Spontaneous magnetisation is characteristic of ferromagnetic materials.
7. 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.
8. In van der walls crystals, there exists a high degree of stability of the outer electron shell.
9. As per temperature limits, the number of categories of solid dielectrics are
10. 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
11. A characteristic property of crystal is its periodicity of structure.
12. 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
13. 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
14. Schrodinger wave equation is a
A. linear equation
B. differential equation
C. partial differential equation
D. none of the above
15. Debye temperature of metals is
A. about 10 K
B. about 200 K
C. about 600 K
D. about 2 K
16. As the viscosity of a liquid increases, the relaxation time
A. remains constant
D. first decreases then increases
17. The materials which become polarized on the application of mechanical stress are called piezoelectric.
18. Which inductor is linear?
A. Air cored
B. Cast iron cored
C. Sheet steel cored
D. Iron alloy cored
19. Which inductor is used at high frequencies?
A. Cast iron cored
B. Sheet steel cored
C. Iron alloy cored
D. Ceramic cored
20. On the basis of the type of chemical bonds, solids may be classified into
A. ionic crystals
B. ionic and valence crystals
C. ionic crystal, valence crystals and metals
D. ionic crystals, valence crystals, metal and vander wall crystals
21. A leakage capacitor can be represented by a capacitance C and resistance R in parallel C.
22. Electric dipole moment is expressed in debye unit.
23. A vacant electronic state moves in the same direction as would a positive charge carrier.
24. Piezoelectricity means the slight change in dimensions of a specimen when an electric field is applied.
25. Many compounds also exhibit semiconducting properties.
MATERIALS and COMPONENTS Questions with Answers pdf ::
26. In a metal, the valence electrons
A. are not shared
B. are shared only between neighbouring atoms
C. are shared by all atoms
D. either (b) or (c)
27. The number of protons in a silicon atom are
28. The fact that domains exhibits spontaneous magnetisation is
A. first hypothesis is of Curie
B. second hypothesis is of Weiss
C. Curie-Weiss law
D. Boltzmann’s statistics
29. 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
30. Nickel is a non-magnetic material.
31. 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
32. 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
33. 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.
34. Which of the following are true for relative dielectric constant?
1. It is dimensionless.
2. It is equal to 1 for vacuum.
3. 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
35. 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
36. The merger of hole and free electron is called
A. covalent bonding
C. thermal energy
D. free electrons
37. Wood is a diamagnetic material.
38. The unit for mmf is
39. A magnetic field exists around
A. moving charges
B. static charges
40. 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
41. 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
42. If the number of atoms per unit volume of a monoatomic gas changes, the dielectric constant still remains constant.
43. The number of protons in a copper atom are
44. 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
45. 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
46. 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
47. The phenomenon of dielectric hysteresis occurs with
C. both ac and dc
D. none of the above
48. As the atoms of rare gases become larger, electronic polarizability
C. remains the same
D. may increase or decrease
49. 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
50. Ferrimagnetic materials have anti-parallel orientation of equal moments of permanent dipoles.
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