# ELECTRONICS AND COMMUNICATION ENGINEERING IMPORTANT MCQ-MATERIALS AND COMPONENTS

1. The dielectric losses do not depend on frequency.

A. True
B. False

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

A. insulator
B. good conductor
C. resistor
D. semiconductor

6. Spontaneous magnetisation is characteristic of ferromagnetic materials.

A. True
B. False

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.

A. True
B. False

9. As per temperature limits, the number of categories of solid dielectrics
are

A. 7
B. 6
C. 8
D. 5

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.

A. True
B. False

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

16. As the viscosity of a liquid increases, the relaxation time

A. remains constant
B. increases
C. decreases
D. first decreases then increases

17. The materials which become polarized on the application of mechanical
stress are called piezoelectric.

A. True
B. False

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.

A. True
B. False

22. Electric dipole moment is expressed in debye unit.

A. True
B. False

23. A vacant electronic state moves in the same direction as would a
positive charge carrier.

A. True
B. False

24. Piezoelectricity means the slight change in dimensions of a specimen
when an electric field is applied.

A. True
B. False

25. Many compounds also exhibit semiconducting properties.

A. True
B. False

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

A. 4
B. 8
C. 12
D. 14

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.

A. True
B. False

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.

A. True
B. False

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
B. recombination
C. thermal energy
D. free electrons

37. Wood is a diamagnetic material.

A. True
B. False

38. The unit for mmf is

A. A
B. Wb
C. T
D. V

39. A magnetic field exists around

A. moving charges
B. static charges
C. iron
D. copper

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.

A. True
B. False

43. The number of protons in a copper atom are

A. 2
B. 9
C. 11
D. 29

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

A. dc
B. ac
C. both ac and dc
D. none of the above

48. As the atoms of rare gases become larger, electronic polarizability

A. increases
B. decreases
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