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Conduction & Semiconducting Materials: Exercises for Engineering Physics II, Exams of Engineering

Vels Institute of Science, Technology & Advanced StudiesEngineering

A collection of exercises and questions related to conduction materials and semiconducting materials, covering topics such as classical free electron theory, fermi level, electrical conductivity, thermal conductivity, hall effect, and more. It is designed for students studying engineering physics ii and provides a valuable resource for practicing and understanding key concepts in solid-state physics.

Typology: Exams

2022/2023

Available from 11/04/2024

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CONDUCTING MATERIALS UNIT I
PART-A (2 Marks)
1. What is mean by conducting materials? Give its example.
2. What is mean by free electron (or) conduction electron?
3. Define classical free electron theory of metal.(CFE)
4. Define Drift velocity. How is it different from thermal velocity of an electron?(AU-JUNE’12)
5. Define Mean free path. (AU- DEC 2002)
6. Define Collision time.
7. Define Relaxation time.(AU - DEC 2003, JUNE 2009)
8. Define Mobility of elections. (AU - MAY 2003, JUNE 2009)
9. DefineElectrical conductivity?(AU -APR 2002)
10. Define Thermal conductivity?
11. Define Fermi leveland Fermi energy level.(AU - APR/MAY 2011,JUNE 2012)
Ans: It is the highest reference energy level of a particle at absolute zero. It is the
state at which the probability of electron occupation is 50% at any temperature.
(Or)
Ans: It is the energy of a state at which the probability of electron occupation is ½
(half) At any temperature above 0K. It is the maximum energy of filled states
at 0K.(Fermi energy level refers to the text book).
12. Mention any two drawbacks of classical free electron theory.(AU - JUNE 2005&2009)
13. Mention any two postulates (merits) of classical free electron theory. (AU - JUNE 2003)
14. Define density of states. What is its use? (AU - DEC 2003)
15. Define Fermi-Dirac distribution function.(AU - MAY 2003)
16. Draw Fermi distribution curve for 0K and at any temperature TK. (or) How does Fermi
function varies with temperature. (AU - Nov 2003)
17. Explain electron theory of solids?
18. What are the main stages in electron theory of solids?
19. State Wiedemann – Franz Law. (AU - DEC 2013)
20. What is a Lorentz number? (AU - JUNE 2004)
21. What is work function?
Ans: The amount of kinetic energy required at absolute zero temperature to move an
electron from the outer orbit at absolute zero temperature is called work function.
22. Mention the merits and demerits of Quantum free electron theory.
__________________IIndSemester Engineering physics – II/Page 1________________________
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CONDUCTING MATERIALS UNIT I

PART-A (2 Marks)

  1. What is mean by conducting materials? Give its example.
  2. What is mean by free electron (or) conduction electron?
  3. Define classical free electron theory of metal.(CFE)
  4. Define Drift velocity. How is it different from thermal velocity of an electron? (AU-JUNE’12)
  5. Define Mean free path. (AU- DEC 2002)
  6. Define Collision time.
  7. Define Relaxation time. (AU - DEC 2003, JUNE 2009)
  8. Define Mobility of elections. (AU - MAY 2003, JUNE 2009)
  9. DefineElectrical conductivity? (AU -APR 2002)
  10. Define Thermal conductivity?
  11. Define Fermi leveland Fermi energy level. (AU - APR/MAY 2011,JUNE 2012) Ans: It is the highest reference energy level of a particle at absolute zero. It is the state at which the probability of electron occupation is 50% at any temperature. (Or)

Ans: It is the energy of a state at which the probability of electron occupation is ½

(half) At any temperature above 0K. It is the maximum energy of filled states at 0K.( Fermi energy level refers to the text book).

  1. Mention any two drawbacks of classical free electron theory. (AU - JUNE 2005&2009)
  2. Mention any two postulates (merits) of classical free electron theory. (AU - JUNE 2003)
  3. Define density of states. What is its use? (AU - DEC 2003)
  4. Define Fermi-Dirac distribution function. (AU - MAY 2003)
  5. Draw Fermi distribution curve for 0K and at any temperature TK. (or) How does Fermi function varies with temperature. (AU - Nov 2003)
  6. Explain electron theory of solids?
  7. What are the main stages in electron theory of solids?
  8. State Wiedemann – Franz Law. (AU - DEC 2013)
  9. What is a Lorentz number? (AU - JUNE 2004)
  10. What is work function? Ans: The amount of kinetic energy required at absolute zero temperature to move an electron from the outer orbit at absolute zero temperature is called work function.
  11. Mention the merits and demerits of Quantum free electron theory. __________________IIndSemester Engineering physics – II/Page 1________________________

PART-B

CONDUCTING MATERIALS

4-MARKS

UNIT I

  1. State the classical free electron theory of metals. ( AU - DEC2013)
  2. How classical free electron theory failed to account for specific heat of solid? (Or) What are the drawbacks of classical free electron theory of metals? ( Refer the Class Notes ) ( AU - JUNE 2007, 12& DEC 2013)
  3. State and prove Wiedemann-Frannz law. ( AU - JUNE 2006,DEC2009,MAY2011)
  4. Obtain Wiedemann-Franz law using the expressions of electrical and thermal conductivity and find the expression for Lorentz number. ( AU - JUNE 2012)
  5. Write the expression for Fermi distribution function and explain with suitable diagram. How does it vary with temperature? (AU - MAY 2011& DEC 2013)
  6. Explain qualitatively the effect of temperature of Fermi function ( AU - JUNE 2012)
  7. What is mean by electrical conductivity? Derive an expression for electrical conductivity of metals based on classical free electron theory. (AU - JUNE 2007, 09,10,12&DEC 2012,13)
  8. What is mean by Thermal conductivity? Derive an expressin for thermal conductivity of a metal based on classical free electron theory. (AU - JUNE 2007, 10&12 & DEC 2013)
  9. Write Fermi-Dirac distribution function. Explain how Fermi function varies with temperature. (AU - MAY 2004, JUNE 2009)
  10. Derive an expression for ‘density of states’ and hence obtain the Fermi energy in terms of density of electrons on the basis of quantum free electron theory. (AU - MAY 2004, JUNE 2010&2012) (Or) Explain the meaning of ‘density of states’. Derive an expression for the number of allowed states per unit volume of a solid. (AU - JUNE 2009, 2010& DEC 2013)
  11. Derive the carrier concentration in metals.(Or) Derive the expression for carrier concentration in terms of Fermi energy. ____________________II ndSemester Engineering physics – II/Page2_________________________

SEMICONDUCTING MATERIALS

4-MARKS

UNIT II

  1. How the Fermi level varies with temperature in an extrinsic semiconductor?
  2. Define Hall coefficient.
  3. Distinguish between intrinsic and extrinsic semiconductors.
  4. What is meant by impurity range?
  5. What is meant by Exhaustion range?
  6. What is meant by intrinsic range?
  7. Differences between Elemental and compound semiconductors (Or) Differences between indirect and direct band gap semiconductors.
  8. Explain the Fermi level and its variation with temperature in intrinsic semiconductor. (AU - Jan 2006)
  9. How does electrical conductivity variation with temperature for an intrinsic semiconductor.
  10. Describe a method of determining the band gap of intrinsic semiconductor. AND ALSO WRITE WITH EXPERIMENTAL
  11. Discuss the variation of Fermi level with temperture in n-type semiconductor. (AU - MAY 2008&DEC 2012)
  12. Discuss the variation of Fermi level with temperature in p-type semiconductor. (AU - DEC 2012)
  13. Difference between n-type and p-type semiconductor. (AU - Jan 2010)
  14. Discuss the variation of carrier concentration with temperature and impurity.
  15. Explain the experimental set up for the measurement of Hall-coefficient. (AU - Nov 2008) ____________________ II ndSemester Engineering physics – II/Page 4__________________

SEMICONDUCTING MATERIALS

PART-B

UNIT II

  1. Derive an expression for the concentration of electrons per unit volume in the conduction band of anintrinsic Semiconductor. (AU - DEC 2005)
  2. Derive an expression for density of holes in the Valence band of an intrinsic semiconductor. and also explain the intrinsic carrier concentration. (AU - MAY 2007)
  3. Derive an expression for carrier concentration in n-type extrinsic semiconductor and explain how the carrier concentration varies with temperature. (AU - MAY 2004& DEC 2013)
  4. Obtain an expression for the electrical conductivity in an intrinsic semi conductor and hence Show how will you determine the band gap Eg of an intrinsic semi conductors. ( AU -DEC‘13)
  5. Derive an expression for density of holes in the valence band of p-type extrinsic semiconductor. (AU - Jan 2008)
  6. Derive an expression for Hall coefficient in the case of n-type and p-type semiconductor. Using Hall effect how will you determine the mobility of harge carriers? (AU - MAY 2011,JUNE2012 &DEC 2012).
  7. Describe a method of determining the bnd gap of a semiconductor. How does electrical Conductivityvaries with temperature for an intrinsic semiconductor. (AU-Nov 2007&JUNE 2012) ____________________ II ndSemester Engineering physics – II/Page 5__________________

MAGNETIC MATERIALS

PART-B

4-MARKS

UNIT III

____

  1. Differentiate between soft and hard magnetic materials. (AU-JUNE 2010, MAY11& DEC 2012)
  2. Explain the anti ferromagnetism and its properties.
  3. Briefly explain different types of magnetic materials and their properties.(Or) (AU- JUNE 2010) Give the classification of magnetic materials on the basis of magnetic susceptibility.
  4. Explain the domain theory of ferromagnetism. (AU- MAY 2011)
  5. Explain domain theory of ferromagnetism and the types of energy involved in the process of Of domain growth in detail.
  6. Explain the hysteresis loop and also explain the hysteresis on the basis of domain theory.
  7. Using the domain theory of ferromagnetism and explain the formation of hysteresis in Ferromagnetic materials. (AU-MAY 2011& DEC 2012&13)
  8. Briefly explain the soft and hard magnetic materials and its properties.
  9. Describe the structure, properties and applications of ferrites. (AU-JUNE 2010& 2012) (Or) What are ferrites? Describe the different types of ferrites structure with suitable diagram. What are the applications of ferrites?
  10. What is meant by eddy current and eddy current losses? Ans: When an alternating magnetic field is applied to the material, it induces an e.m.f and Sets up a large current in the material. This current is known as eddy current and the Power loss is called eddy current losses.
  11. In what from data are stored in magnetic tapes? Ans: Information recorded in the magnetic tape is in the form of tiny magnetised and non magnetised spots on the metal oxide coating. The magnetised spot represent ‘1’ and unmagnetised spot represent ‘0’ in binary code. The information can be accessed, processed , erased and can be again stored in the same area. ____________________ II ndSemester Engineering physics – II/Page 7____________________

SUPERCONDUCTING MATERIALS

4-MARKS

UNIT III

PART-A (2 Marks)

  1. Explain the phenomenon of super conductivity. (AU-April 2002,2003)
  2. What is transition temperature (or) critical temperature? (AU-Jan 2005)
  3. What is meissner effect? (AU-April 2003, MAY 2007)
  4. What are high temperature superconductors? Give examples. (AU-April 2003)
  5. Explain the term critical magnetic field in superconductor. (AU-MAY 2004)
  6. What is an isotope effect in superconductivity? (AU-MAY 2006)
  7. What are high TC superconductors? Give an example. (AU-MAY 2004)
  8. Explain the properties of superconductor. (AU-MAY 2006)
  9. Mention the applications of superconductors. (AU-Jan 2003)
  10. What are type I superconductor? (AU-MAY 2007)
  11. What is type II superconductor? (AU-MAY 2007)
  12. What is low temperature of superconductor?
  13. What are cooper pairs? (AU-JUNE 2012)
  14. Differentiate between Type I and Type II superconductor. (AU-Jan 2004, MAY 2011, JUNE 2010 & DEC 2012) (Or) Differentiate between soft and hard superconductor.
  15. Write short notes on Josephson Junctions.
  16. Write short notes on Magnetic levitation.(or) State the use of Magnetic levitaion. (AU-DEC 2012)
  17. Explain the effect of isotopes in superconductors. (AU-MAY 2003)
  18. Explain Meissner effect. (AU-JUNE 2010)
  19. Write a note on SQUID.
  20. Explain the operation of a cryotron.
  21. List any four applications of superconductors. ____________________ II ndSemester Engineering physics – II/Page 8__________________

DIELECTRIC MATERIALS

4-MARKS

UNIT IV

PART-A (2 Marks)

  1. Define Electric dipole and Dipole moment.
  2. Define Dielectric constant (εr). (AU-JUNE 2003& 2012)
  3. Define Polarization (or) Polarizationof dielectric materials. (AU-JUNE 2004)
  4. Define Polarisability (α) and Polarization vector. (AU-JUNE 2012)
  5. Define Electric displacement vector.
  6. Define Electric flux density. (AU-JUNE 2012)
  7. What is electric susceptibility? (AU-MAY 2011& JUNE 2012)
  8. Define Space-charge Polarization? (AU-DEC 2013)
  9. What is meant by local field (or) internal field in a dielectric? (AU-Jan 2004& DEC 2012)
  10. Define dielectric loss and loss angle. (AU-MAY 2005)
  11. Define dielectric breakdown and dielectric strength. (AU-Jan 2003& JUNE 2012)
  12. Mention a few applications of dielectrics.
  13. What is ferro electricity?
  14. What are active and passive dielectrics? Give examples.
  15. What is pyroelectricity? (AU-DEC 2013)
  16. State the properties of ferroelectric materials. (AU-JUNE 2010)
  17. Give any four applications of ferroelectric
  18. What is effect of frequency on polarization? aterials. Ans: (i) The electronic an ionic polarizations are independent of temperature. (ii) The orientation polarizationDECreases with the increase in temperature. where as the space charge polarization increases with the increase in temperature.
  19. Define Total polarization (or) Langevin-Debye equation.
  20. Obtain Clausius-Mosotti equation. (AU-DEC 2009)
  21. Explain dielectric loss and derivethe expression for dielectric loss.
  22. Define intrinsic breakdown and Avalanche breakdown. (AU-MAY 2002)
  23. What is Discharge and Defect breakdown? (AU-Jan 2003,2004)
  24. What is thermal breakdown? (AU-MAY 2005)
  25. What is chemical and electro chemical breakdown? (AU-MAY 2004)
  26. Describe the frequency dependence of polarization of a dielectric material. (AU-JUNE 2010)
  27. Describe the applications of dielectric materials in capacitor and transformer. ____________________ II ndSemester Engineering physics – II/Page 10_______________________

DIELECTRIC MATERIALS

PART-B

UNIT IV

  1. Explain the different types of polarization mechanisms involved in a dielectric material. (AU-April 2002, MAY 2011)
  2. (i) Discuss electronic and ionic polarizations with examples. (ii) Obtain an expression for the above polarization. (AU- DEC 2013)
  3. Derive an expression for local field (or) in a dielectric material. Deduce Clausius Mosotti Equation. (AU-JUNE2009, 2010, MAY 2011, JUNE 2012 &DEC 2012& 2013) (Or) Define internal field.Obtain the expression for internal field using Lorentz method and hence deduce the clausisus-mosotti equation. (AU-JUNE 2012, DEC 2013)
  4. Discuss in detail the different dielectric breakdown mechanisms. (AU-JUNE 2010, DEC2011) &(Page number: 5.37-5.42, Tpic: 5.11)
  5. Explain electronic polarization in atoms and obtain an expression for electronic polarization in terms of the radius of atoms. (AU-DEC 2012)
  6. Explain the effects of frequency ad temperature on various polarization mechanisms of dielectrics. (AU-MAY 2011)
  7. What is ferroelectricity? Explain the hysteresis curve exhibited by a ferroelectric material with a suitable sketch. Give its examples. (AU-JUNE 2009) (Or) (i) Explain ferroelectric materials and their properties. ____________________ II ndSemester Engineering physics – II/Page 11__________________
  1. What are nano materials? Give examples. (AU-JUNE 2007)
  2. What are the properties of nano particles?
  3. What are the two routes through which nano particles can be synthesized?
  4. Define Top-down process with example.
  5. Define Bottom –up process with example.
  6. Mention the techniques for synthesis of nano phase materials.
  7. What is sol-gel?
  8. List out the different forms of nanomaterials.
  9. What is meant by plasma arching?
  10. What are the different structures of carbon nanotubes? (AU-MAY 2011)
  11. What are carbon nanotubes (CNT)? (AU-DEC 2013)
  12. What is fullerene? (AU-JUNE 2012)
  13. What are the applications of carbon nanotubes? (AU-JUNE 2010)
  14. What are single walled CNT and multiwall CNT?
  15. What are shape memory alloys? Write their characteristics. List out the applications of shape memory alloys. (AU-Nov 2002& DEC 2012, DEC 2013)
  16. Describe a technique to synthesize nanophase materials. (AU-JUNE 2006) (or) Explain how nanoparticles can be produced using following technique. (AU-JUNE&DEC’12) (i) Chemical vapour deposition (AU-JUNE 2012) (ii) Pulsed Laser deposition. (iii) (iv) Electro depositions. (AU-DEC 2013) Sol-gels (AU-JUNE 2012 , DEC 2013)
  17. Explain the Physical, Magnetic and Mechanical Properties of carbon nanomaterials. (AU- JAN 2012)
  18. Explain the Applications of carbon nanophase materials. (AU- JAN 2010, DEC 2012)

NANO MATERIALS

PART-B

UNIT V

PART-A (2 Marks)

____________________ II nd^ Semester Engineering physics – II/Page13__________________

NAN-LINEAR MATERIALS & BIO-MATERIALS UNIT V

  1. What is Birefringence? Explain Kerr effect.
  2. Explain non-linear properties and second harmonic generator.
  3. Explain Biomaterials with their properties and applications. 
    **ALL THE BEST**

__________________ II ndSemester Engineering physics – II/Page14__________________