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Materials and Components problems


  • 1. The resistivity of intrinsic semiconductors, at room temperature, is of the order of

  • Options
  • A. 1 ?-m
  • B. 1000 ?-m
  • C. 106 ?-m
  • D. 10-3 ?-m
  • Discuss
  • 2. The electric dipole moment of a neutral system of point charges Q1, Q2.... is Electronics and Communication Engineering Materials and Components: The electric dipole moment of a neutral system of point charges Q1, Q2.... is Qiri . The charges Qi

  • Options
  • A. must be all positive
  • B. must be all negative
  • C. must be such that Qi = 0
  • D. either (a) or (b)
  • Discuss
  • 3. If m, v, r are the mass, velocity and radius of orbit of electron and h is Planck's constant, quantum condition for electron's orbit is

  • Options
  • A.
  • B.
  • C.
  • D.
  • Discuss
  • 4. The capacitance of an insulated conducting sphere of radius R in vacuum is

  • Options
  • A. 2p?0R
  • B. 4p?0R
  • C. 4p?0R2
  • D. 4p
  • Discuss
  • 5. Thermistor is used in

  • Options
  • A. temperature measurement
  • B. temperature control
  • C. high temperature alarm circuits of devices
  • D. all of the above
  • Discuss
  • 6. The hysteresis loss is

  • Options
  • A. proportional to frequency
  • B. independent of frequency
  • C. proportional to (frequency)2
  • D. proportional to
  • Discuss
  • 7. Resistivity of rubber is about

  • Options
  • A. 102 ?-m
  • B. 10-2 ?-m
  • C. 5 x 108 ? m
  • D. 5 x 1012 ?-m
  • Discuss
  • 8. In terms of classical representation of electrons

  • Options
  • A. an atom is essentially empty
  • B. an atom is essentially full
  • C. an atom may be essentially empty or full depending on the material
  • D. an atom may be essentially empty or full depending on temperature
  • Discuss
  • 9. Some typical examples of macroscopic quantities are

  • Options
  • A. conductivity
  • B. µr
  • C. dielectric constant
  • D. all of the above
  • Discuss
  • 10. Assertion (A): For a magnetic material M = (?r - 1) H, where M is magnetic dipole moment/m3, H is field intensity A/m and ?r is relative permeability.

    Reason (R): ?r can have any value from 0 to hundreds of thousands.


  • Options
  • 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
  • Discuss

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