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  • Question

  • In a pure sample of silicon


  • Options
  • A. the number of holes and free electrons is always equal
  • B. the number of free electrons is more than the number of holes
  • C. the number of free electrons and holes is equal at low temperature
  • D. the number of free electrons is less than number of holes

  • Correct Answer
  • the number of holes and free electrons is always equal 

    • Materials and Components problems

    Search Results

    • 1. Which of the following is the poorest conductor of electricity?

    • Options
    • A. Aluminium
    • B. Nichrome
    • C. Copper
    • D. All of the above
      • Discuss
    • 2. A permeable substance is one

    • Options
    • A. which is strong magnet
    • B. which is a weak magnet
    • C. which is a good conductor
    • D. through which magnetic lines of force can pass easily
      • Discuss
    • 3. Ferrites have

    • Options
    • A. a low copper loss
    • B. low eddy current loss
    • C. low resistivity
    • D. higher specific gravity compared to iron
      • Discuss
    • 4. The number of valence electrons in acceptor impurity are

    • Options
    • A. 5
    • B. 4
    • C. 3
    • D. 1
      • Discuss
    • 5. In a specimen of ferromagnetic material, as the flux density is increased from zero to 2.5 T, µr will

    • Options
    • A. increase
    • B. decrease
    • C. first decrease then increase
    • D. first increase then decrease
      • Discuss
    • 6. In intrinsic semiconductors, the number of free electrons is equal to the number of mobile holes.

    • Options
    • A. True
    • B. False
      • Discuss
    • 7. Assertion (A): In a parallel plate capacitor having area of plate 1 m2 and plate separation 1 m, the capacitance C and resistance R are given by C = ?0?'r and R = where ? is frequency, ?r' and ?r" are real and imaginary parts of dielectric constant.

      Reason (R): The imaginary part of electric constant is responsible for dielectric losses.


    • 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
    • 8. Assertion (A): When an electron is revolving in its orbit and magnetic field is also present, the angular frequency of electron will be affected by the magnetic field.

      Reason (R): In the case of electron revolving in its orbit in the presence of magnetic field, the orbital magnetic dipole moment is not affected by the presence of magnetic field.


    • 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
    • 9. When subjected to alternating stresses, an insulating material is characterised by complex dielectric constant ?'r - j?"r . In such materials, the dielectric losses under alternating stress is proportional

    • Options
    • A. ?"r
    • B. both ?'r and ?"r
    • C. ?'r
    • D. (?"r)2
      • Discuss
    • 10. Assertion (A): Relaxation time and mean time between collisions are equal when scattering is isotropic.

      Reason (R): Mean free path of an electron ?, velocity of electron v and mean time between collisions tc are related as ? = vTc.


    • 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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