Conducting Material2

Conducting materials 1

Question Bank- Engineering Physics- II- Nandha Engineering College ( Autonomous)

UNIT 1 – CONDUCTING MATERIALS

PART A

1.     Classify the solid materials based on their conductivity.

2.     Define free electrons

3.     State classical free electron theory.

4.     State quantum free electron theory.

5.     State band theory

6.     What is drift velocity?

7.     Define mobility of an electron

8.     State Ohm’s law.

9.     What is co-efficient of electricity?

10.            Write an expression for electrical conductivity.

11.            Define the thermal conductivity of materials..

12.            State Widemann – Franz law.

13.            Define Lorentz number and give its value.

14.            Distinguish between electrical and thermal conductivity.

15.            State the success and drawbacks of classical free electron theory.

16.            Define Fermi energy level.

17.            State the Fermi function.

18.            Define the density of state.

19.            What is carrier concentration of a metal?

20.            Define work function.

21.            What is Fermi – Dirac distribution function?

22.            Define relaxation time.

23.            Define the terms ‘mean free path’ and ‘mean collision time.

24.            Why I = E/ρ is called microscopical form of Ohm’s law.

25.            Evaluate the value of Fermi distribution function for an energy KT above the Fermi energy.

PART B

1.     How the electron moving differs with respect to the applied electric field?

2.     Distinguish between the electrical and thermal conductivity.

3.     Mention the drawbacks of classical free electron theory.

4.     List out the success of classical free electron theory.

5.     What is Fermi energy level and give its importance?

6.     How the temperature affects the Fermi function

7.     Show that the Fermi energy at 0K is

8.     Show that the Fermi energy at 0K is

PART C

1.     Obtain the expression for electrical conductivity

2.     Show the thermal conductivity of a conductor is

3.     Define Wiedemann-Franz law and how the Lorentz number differs by comparing classical and quantum theories.

4.     Discuss the energy distribution of electrons in metals.

5.     Obtain the expression of density of states for conductors.

6.     What is work function? List out the different energies employed for work function

UNIT 2 – SEMICONDUCTING MATERIALS

PART A

1.     Define semiconductors.

2.     Classify the semiconductors to various types.

3.     Define elemental semiconductors and give some examples.

4.     Define compound semiconductors and give some example.

5.     What is an intrinsic semiconductor and give some examples.

6.     What is an extrinsic semiconductor and give some examples.

7.     Define P – type and N- type semiconductors?

8.     What is doping?

9.     What is an impurity and give the types of impurities?

10.                        What are the properties of semiconductors?

11.                        Distinguish between elemental and compound semi – conductors.

12.                        Define valence electron and conduction electron.

13.                        What is conduction band and valence band?

14.                        What is an energy band?

15.                        What is forbidden energy gap?

16.                        What is positive temperature co-efficient of resistance?

17.                        What is negative temperature co-efficient of resistance?

18.                        Write the expressions for Density of electrons in conduction band and density of holes in valence band.

19.                        Write notes on intrinsic carrier concentration.

20.                        How the P – type and N – type semiconductors are formed?

21.                        State the Hall – Coefficient and hall voltage.

22.                        Write an expression for Hall co-efficient in terms of Hall voltage.

23.                        List out the applications of Hall Effect.

24.                        What are donors and acceptors?

25.                        How the Fermi level varies with temperature in an extrinsic semiconductor?

26.                        How the Fermi level varies with temperature in an intrinsic semiconductor?

27.                        What happens when the temperature increases in the case of semiconductors and conductors?

28.                        How will you distinguish N-type and P-type semiconductors using Hall-co-efficient?

29.                        What is Fermi level in semiconductors?

30.                        Why we prefer Si for transistors and GaAs for diodes.

PART B

1.     Discuss about elemental and compound semicondutors

2.     Classify the semiconducting materials.

3.     State negative temperature co-efficient of resistance.  How the electrical conductivity of a semiconductor is directly proportional to the temperature

4.     How to determine the band gap energy of intrinsic semiconductors.

5.     How P – type semiconductors are formed?

6.     How N – type semiconductors are formed?

7.     List out any four applications of Hall effect.

8.     Obtain an equation for Hall coefficient in terms of Hall voltage.

9.     Discuss the experimental determination of Hall Effect.

PART C

1.     What are semiconductors? List out any four properties of semiconductors?

2.     Distinguish between elemental and compound semiconductors.

3.     Derive the expressions for density of holes in valence band

4.     Derive the expressions for density of electrons in conduction band.

5.     How the temperature affects the Fermi energy level and carrier concentration in an intrinsic semiconductors.

6.     Obtain the density of electrons and holes in terms of E_g in intrinsic semiconductors.

7.     Obtain the expression for Fermi energy of N- type semiconductors.

8.     How the temperature affects the Fermi energy level and carrier concentration in N - type semiconductors.

9.     Obtain the expression for Fermi energy of P- type semiconductors.

10.            How the temperature affects the Fermi energy level and carrier concentration in P - type semiconductors.

11.            State Hall Effect.  What are the importances of Hall Effect.

12.            Discuss the Hall Effect in P-type semiconductors.

13.            Discuss the Hall Effect in N-type semiconductors.

UNIT 3 – DIELECTRIC MATERIALS

PART A

1.     Define an insulator.

2.     What are dielectrics?

3.     What is an electric polarization?

4.     What is electric susceptibility?

5.     What is the relation between P and E?

6.     What is dielectric constant?

7.     Classify the dielectrics.

8.     What are active and passive dielectrics?

9.     Give some examples for active and passive dielectrics.

10.                        What are polar and non – polar dielectrics?

11.                        Distinguish between polar and non – polar molecules.

12.                        What are the types of electric polarization?

13.                        What is an electronic polarization?

14.                        What is an ionic polarization?

15.                        What is an orientation polarization?

16.                        What is space charge polarization?

17.                        Write down an expression for total polarization in dielectric materials.

18.                        Write an expression for Claussius Mossotti relation.

19.                        Define dielectric loss.

20.                        What is dielectric break down?

21.                        What are the types of dielectric breakdown?

22.                        What is an intrinsic break down?

23.                        What is an avalanche breakdown?

24.                        What is thermal breakdown?

25.                        What is chemical; and electrochemical breakdown?

26.                        What is discharge breakdown?

27.                        What is defect breakdown?

28.                        What are the applications of dielectrics?

29.                        What are the remedies for breakdown mechanisms?

30.                        State Ferro electricity.

31.                        What is curies temperature in dielectrics?

32.                        What are non-linear dielectrics?

33.                        What is spontaneous magnetization?

34.                        What are the applications of Ferro electric materials?

35.                        What is Piezo – electricity?

PART B

1.     Discuss the orientation polarization in dielectric materials.

2.     Obtain the total electric polarization in dielectrics.

3.     List out the various types of dielectric breakdown.

4.     State ferro electricity and ferro electrics.

5.     Explain the hysteresis curve for ferro electricity.

6.     List out the types of dielectric breakdown.

PART C

1.     Write a brief note about the electrical susceptibility and dielectric constant.

2.     Obtain an expression for electronic polarization in dielectric materials.

3.     Derive an expression for ionic polarization in dielectric materials.

4.     How the frequency and temperature affects the electrical polarizations of dielectrics.

5.     What is meant by local field in a dielectric and how it is calculated?

6.     Deduce Clussisus Mossotti relation.

7.     Discuss about the loss in dielectrics.

8.     Explain the various types of dielectric breakdown.

9.     What are the uses of dielectrics in capacitors?

10.                        What are the uses of dielectrics in transformers?

11.                        List out the properties of ferro electricity.

12.                        List out the applications of ferro electricity.

UNIT IV – THERMAL PHYSICS

PART A

1.     State the thermodynamics of a matter.

2.     What is thermal conduction?

3.     What is thermal conductivity of a substance?

4.     What are the models of heat transfer?

5.     State the laws of thermodynamics.

6.     State the Newton law of cooling.

7.     What are phonons?

8.     State the thermal diffusivity of materials.

9.     What are good conductors?

10.                        What are bad conductors?

11.                         List the methods used for study the thermal conductivity of good and bad conductors.

12.                        What are the types of radial flow of heat?

13.                        What are the basic entities responsible for thermal conduction of a solid?

14.                         Distinguish between electrical and heat conduction.

15.                        What are the demerits of Forbe’s experiment of estimating thermal conductivity of good conductors?

16.                         What is the operational principle of Lee’s disc?

PART B

1.     Solve the theory of heat flow along a bar for steady state condition.

2.     Discuss the special cases of heat flow along a bar.

3.     List out the merits and demerit in Forbe’s method experiment for the determination of thermal conductivity of good conductors.

4.     List out the practical applications of conduction.

PART C

1.     Discuss the theory of heat flow along a bar.

2.     Discuss the theory of thermal conductivity of good conductors.

3.     Discuss the Forbe’s method experiment for the determination of thermal conductivity of good conductors.

4.     Discuss the theory of thermal conductivity of bad conductors.

5.     Discuss the Lee’s method experiment for the determination of thermal conductivity of bad conductors.

6.     Discuss the radial flow of heat through the sides of a tube.

7.     Discuss the radial flow of heat through the wall of a spherical shell.

8.     Discuss the thermal conductivity of rubber.

UNIT 5 – NON – DESTRUCTIVE TESTING

PART A

1.     What is meant by non destructive testing?

2.     What is meant by destructive testing?

3.     Distinguish between destructive and non-destructive testing methods.

4.     What are the types of NDT methods?

5.     What is radiography?

6.     What is meant by radiation gauging?

7.     What is meant by fluoroscopy?

8.     What are the classifications of testing methods?

9.     What are the types of radiography?

10.                        Define exposure factor.

11.                        What are the applications of X – ray radiographic techniques?

12.                        What is the working principle of X – ray radiographic displacement method?

13.                        What are the merits and demerits of X – ray radiographic displacement method?

14.                        What are the limitations of X – ray radiographic displacement method?

15.                        What is meant by liquid penetrant testing?

16.                        What is the basic principle of liquid penetrant testing?

17.                        What are the characteristics of liquid pentrant testing materials?

18.                         What are the applications of liquid pentrant testing method?

19.                         What the limitations of liquid pentrant testing method?

20.                        What are the advantages of liquid pentrant testing method?

21.                        What are the radiation hazards in radiology?

22.                        What are inspection methods in ultrasonic inspection techniques?

23.                        What is the working principle of ultrasonic flaw detector?

24.                        What are the merits of ultrasonic flaw detection method?

25.                        What are the demerits of ultrasonic flaw detection method?

26.                        What are the applications of ultrasonic methods?

27.                         What are the limitations of tltrasonic methods

28.                         What is mean by thermography?

29.                        What is basic principle of thermo grapy technique?

30.                         What are the advantages of thermo graphic studies?

31.                        What are the applications of thermo graphic studies?

PART B

1.     Discuss the production of x ray radiography

2.     List out the merits and demerits of X – ray radiography

3.     What are the applications of X – ray radiography

4.     What are the advantages and disadvantages of X-ray fluoroscopy?

5.     What are the applications of X – ray fluoroscopy?

6.     What are the advantages and disadvantages of liquid penetrant method?

7.     What are the applications of liquid penetrant method?

8.     What are the advantages and disadvantages of ultrasonic flaw detection?

9.     What are the types of thermographic techniques?

10.                        What are the merits and demerits of thermographic techniques?

11.                        What are the tapplications of thermographic techniques?

PART C

1.     Discuss the X – ray radiographic displacement method

2.     Discuss the X – ray fluoroscopy technique

3.     Discuss the experimental procedure for liquid pentrant method

4.     Discuss the method of ultrasonic flaw detector

5.     Explain the construction of thermo graphic technique.

6.     How did you record the thermographic images?

1.     Discuss the production of x ray radiography

2.     List out the merits, demerits and applications of X – ray radiographic techniques

3.     List out the merits demerits and applications of liquid pentrant method