21. Ceramic resonators use which one of the following?
- (a) Barium titanate
- (b) Silicon
- (c) Piezoelectric quartz crystal
- (d) Zirconium titanate
22. Which among the following has capacitance value(s) from a few microfarads to a high microfarad?
- (a) Mica, glass, low-loss ceramic
- (b) High permittivity ceramic
- (c) Paper
- (d) Electrolytic
23. How much is the frequency-independent power factor of a plastic dielectric capacitor?
- (a) 0.00002
- (b) 0.0002
- (c) 0.002
- (d) 0.02
24. The velocity of light in a particular medium is 108 m/s. What is the relative permittivity of the medium?
- (a) 1.732
- (b) 3
- (c) 9
- (d) 0.333
25. What does the quality factor of a dielectric mean?
- (a) it is related to the value of the permittivity of the material
- (b) It is related to the breakdown voltage of the dielectric
- (c) It is related to the resistivity of the material
- (d) it is related to the ratio between maximum stored energy and average power loss in the dielectric
26. In highly stable oscillator circuits, AT-cut quartz crystals are generally employed. What is the reason for using this particular orientation?
- (a) Quantza crystals have a natural growth along this plane
- (b) The corresponding quality factor is the largest for orientation
- (c) There is minimal temperature variation in frequency
- (d) AT-cut crystal can be used over a wide frequency range
27. Which one of the following is not a characteristic of a ferroelectric material?
- (a) High dielectric constant
- (b) NO hysteresis
- (c) Ferroelectric characteristics only above the curie point
- (d) Electric dipole moment
28. Which one of the following materials is not a piezoelectric material?
- (a) BaTiO3
- (b) Quartz
- (c) Rochelle salt
- (d) Yttrium garnet
29. The resonance frequency of a quartz crystal oscillator shows the least variation with temperature when the orientation of the crystal is chosen to have
- (a) X-cut
- (b) Y-cut
- (c) NT-cut
- (d) AT-cut
30. The capacitor per unit volume is the maximum for
- (a) air capacitor
- (b) mic capacitor
- (c) ceramic capacitor
- (d) electrolytic capacitor
31. Which of the following material is not an insulator?
- (a) Diamond
- (b) Graphite
- (c) Bakelite
- (d) Lucite
32. Effective Q of the equivalent electrical circuit of a quartz crystal is of the order of
- (a) 200
- (b) 2000
- (c) 20,000
- (d) 2,00,000
33. No-polar electrolytic capacitors
- (a) are used for applications in AC circuits without any DC polarizing voltage
- (b) contain two capacitors connected in series with opposing polarities
- (c) both (a) and (b) are correct
- (d) both (a) and (b) are wrong
34. In a piezoelectric crystal oscillator, if x represents the mass of the crystal, then the oscllation or tuning frequency is linearly proportional to
- (a) the mass of the crystal
- (b) the square root of the mass of the crystal
- (c)the square of the mass of the crystal
- (d) the inverse of the square root of the mass of the crystal
35. The three kinds of breakdowns possible in the solid dielectric are electrothermal, purely electrical and
- (a) electromechanical
- (b) purely thermal
- (c) electrochemical
- (d) spontaneous
36. Commonly used dielectric in electrolytic capacitors is
- (a) magnesium oxide
- (b) cadmium nitride
- (c) aluminum oxide
- (d) manganese oxide
37. In some substances when an electric field is applied the substance becomes polarized. The electrons and nuclei assume new geometrical positions and the mechanical dimensions are altered. This phenomenon is called
- (a) Electrostriction
- (b) Hall-effect
- (c) Polarization
- (d) Magnetization
38. Electrical conductivity, thermal conductivity, and magnetic properties of ceramic material are
- (a) very high all the time
- (b) very low all the time
- (c) dependent on the material
- (d) ascertainable, instance to instance
39. Electrochemical breakdown in a dielectric occurs at
- (a) very low temperature only
- (b) very high temperature only
- (c) very high temperature concurrent with high humidity of the surroundings
- (d) very low temperature concurrent with ambient humidity above 50%
