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Materials and Components problems


  • 1. The induced magnetic dipole moment has a direction opposite to the applied magnetic field.

  • Options
  • A. True
  • B. False
  • Discuss
  • 2. A sample of N type semiconductor has an electron density of 6.25 x 1018/cm3 at 300 K. If intrinsic concentration of carriers in this sample is 2.5 x 1013/cm3 at this temperature, the hole density is

  • Options
  • A. 106 / cm3
  • B. 108 / cm3
  • C. 1010 / cm3
  • D. 1012 / cm3
  • Discuss
  • 3. When an electron moves at velocity v in combined electric and magnetic fields E and H, the Lorentz force F is F = - e(E + v x B).

  • Options
  • A. True
  • B. False
  • Discuss
  • 4. Iron has a body centred cubic structure.

  • Options
  • A. True
  • B. False
  • Discuss
  • 5. Sulphur hexafluoride is used in

  • Options
  • A. transformers
  • B. generators
  • C. relays
  • D. circuit breakers
  • Discuss
  • 6. A rare gas has N atoms per m3. If electronic polarizability of single atom of this gas is ae, then

  • Options
  • A. ?r = Nae
  • B. ?0?r = Nae
  • C. ?0(?r - 1) = Nae
  • D. ?0(?r - 2) = Nae
  • Discuss
  • 7. M = (?r - 1)H.

  • Options
  • A. True
  • B. False
  • Discuss
  • 8. A parallel plate capacitor has area of plate equal to 1 m and distance between plates is also 1 m2. The lossy dielectric has a complex dielectric constant ?r = ?'r - j ?"r. If the capacitor is represented by R and C is parallel, then

  • Options
  • A.
  • B.
  • C.
  • D.
  • Discuss
  • 9. Which of the following is used in temperature alarm circuits?

  • Options
  • A. Thermistor
  • B. Photoconductor
  • C. Transistor
  • D. Varistor
  • Discuss
  • 10. The v-i characteristic shown in the given figure is for
    Electronics and Communication Engineering Materials and Components: The v-i characteristic shown in the given figure is for

  • Options
  • A. thermistor
  • B. photoconductor
  • C. varistor
  • D. none of the above
  • Discuss

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