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  • Question

  • 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

  • Correct Answer
  • Both A and R are true but R is not correct explanation of A 

    • Materials and Components problems

    Search Results

    • 1. 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
    • 2. 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
    • 3. 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
    • 4. In intrinsic semiconductors, the number of free electrons is equal to the number of mobile holes.

    • Options
    • A. True
    • B. False
      • Discuss
    • 5. 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
      • Discuss
    • 6. Assertion (A): CO2 has no resultant dipole moment but CO has a dipole moment.

      Reason (R): The structure of CO2 is O = C = O.


    • 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
    • 7. Paramagnetic materials have permanent magnetic dipoles but interaction between neighbouring dipoles is negligible.

    • Options
    • A. True
    • B. False
      • Discuss
    • 8. Assertion (A): Copper is a monoatomic solid.

      Reason (R): In a metal the valence electrons belong to all atoms.


    • 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. If q is charge on an electron, R is radius of electron orbit and ? is angular velocity of electron rotation, the magnetic dipole moment of electron in orbit is

    • Options
    • A. 0.5 q?R
    • B. 0.5 q2?2R2
    • C. 0.5 q?R2
    • D. 0.5 q?2R
      • Discuss
    • 10. The classes of solid dielectrics are

    • Options
    • A. A, B, C, D, E, F, H
    • B. A E B F H C D
    • C. Y A E B F H C
    • D. A E B F H C
      • Discuss

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