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EXERCISES

EXERCISES

  1. 1.       Elucidate the difference between the classical free electron theory and quantum free electron theory.
  2. 2.       State the main assumption of Sommerfeld’s free electron theory of metals.
  3. 3.       Define Fermi energy and Fermi factor. Discuss about the variation of Fermi energy with temperature and energy.
  4. 4.       Give an account of Fermi factor and define the same.
  5. 5.       What is Fermi factor? Give the theory of calculation of Fermi energy is 0K.
  6. 6.       What is physical basis for concept of Fermi energy? What is the assumptions made for Fermi energy at T>00K? Justify the same.
  7. 7.       Discuss the dependence of Fermi factor on temperature.
  8. 8.       Discuss the probability of occupation of various energy states by electron at T=0K and T>0, on the basis of Fermi factor.
  9. 9.       Give the concept of discrete energy levels for the atomic state and account for the formation of energy bands in the solid state.
  10. 10.    Explain band theory of solids.
  11. 11.    Describe the concept of energy bands in solids.
  12. 12.    What are the essential features of Band theory of solids?
  13. 13.    Describe the periodic potential of solid for which Bloch’s theorem is applied.
  14. 14.    Explain the motion of free electrons in periodic lattice.
  15. 15.    Explain the classification of solids on the basis of energy band theory.
  16. 16.    Discuss the motion of electrons in a region of periodic potential. How can one understand electrical conductivity in a solid?
  17. 17.    Discuss the essential features of electron energy band structures of solid on the basis of Kronig-Penney model.
  18. 18.    Discuss Kronig-Penney model. Using the model show the energy spectrum of electron consisting of a number of allowed energy bands separated by forbidden bands.
  19. 19.    Distinguish between conductor, semiconductor and insulator on the basis of band theory of solids.
  20. 20.    Obtain an expression for carrier concentration of holes in intrinsic semiconductor.
  21. 21.    Obtain an expression for carrier concentration in an N-type semiconductor.
  22. 22.    Obtain an expression for carrier concentration of charges in P-type semiconductor.
  23. 23.    What are traps? Discuss simple model to show the effect of traps on the photoconductivity. Calculate the gain factor.
  24. 24.    What is photoconductivity? State the principle of photoconductive cell. Describe construction, working and use. Show the illumination characteristic and spectral response.
  25. 25.    What is photovoltaics? Discuss the energy conversion process in a photovoltaic cell/solar cell.
  26. 26.    What is superconductivity? What are the basic aspects of it?
  27. 27.    Describe Meissner’s effect. Distinguish between Type I and Type II superconductors. Write various applications of superconductors.
  28. 28.    Explain in detail the BCS theory of superconductivity.
  29. 29.    Describe and explain following:
    1. Meissner’s effect
    2. Isotope effect
    3. BCS Theory
    4. 30.    Prove the Meissner effect contradicts the Maxwell’s equation.