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  • Question
  • Assertion (A): If WF is Fermi energy, v is velocity of electron and m is mass of electron, then Assertion (A): If WF is Fermi energy, v is velocity of electron and m is mass of electron, then . Re.

    Reason (R): Conductivity of a metal depends on temperature and impurity concentration.


  • 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. For a photoconductor with equal electron and hole mobilities and perfect ohmic contacts at the ends, an increase in intensity of optical illumination results in

    • Options
    • A. a change in o.c voltage
    • B. a change in s.c current
    • C. decrease in resistance
    • D. increase in resistance
    • Discuss
    • 2. 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
    • 3. 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
    • 4. 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
    • 5. Paramagnetic materials have permanent magnetic dipoles but interaction between neighbouring dipoles is negligible.

    • Options
    • A. True
    • B. False
    • Discuss
    • 6. The temperature below which certain materials are antiferromagnetic and above which they are paramagnetic is called

    • Options
    • A. Weiss temperature
    • B. Curie temperature
    • C. Neel temperature
    • D. None of the above
    • Discuss
    • 7. Assertion (A): When cathode temperature is increased from 2500 K to 2550 K, thermionic emission current may increase by about 50%.

      Reason (R): Thermionic emission current ? T2 e-Ew/kT.


    • 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): Silicon is the most favoured semiconductor material.

      Reason (R): PIV for silicon diode is more than that for germanium diode.


    • 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. Assertion (A): Magnetism can be explained by the theory of magnetic domains.

      Reason (R): The existence of magnetic domains is evident from the Bitter powder patterns.


    • 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
    • 10. In crystalline solids, atoms are stacked in a regular manner.

    • Options
    • A. True
    • B. False
    • Discuss


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