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					            BOARD OF TECHNICAL EDUCATION
                               PORVORIM-GOA
                          November,2010 Examinations

Programme: Electrical Engineering

Subject: Electrical Engineering Materials(4101)

Time Duration: 3 Hrs.                                    Max. Marks: 75
Instructions: 1) All Questions are compulsory.
              2) Figures to the right indicate full marks.
              3) Assume suitable additional data if required.

Q.No.1. Answer any five of the following Questions:                          (5 x 3 = 15)
     a) Discuss the various conductor materials used in overhead
         transmission line.
     b) Define the terms resistivity and conductivity as applied to
         engineering materials.
     c) State the merits of semiconductor devices used in electrical
         industry.
     d) Define Dielectric loss and explain the term breakdown voltage of
         a dielectric.
     e) State the difference between an insulator and a dielectric.
      f) What are soft and hard magnetic materials?
     g) Discuss the applications of Radioactive materials.

Q.No.2. Answer any two of the following Questions:                           (2 x 6 = 12)
     a) What are the main alloys of copper? List out the properties and
        uses of any two such alloys.
     b) State the advantages and disadvantages of Aluminium as
        compared to copper.
     c) Discuss the conducting materials used for transformers and
        rotating electric machines along with their properties.

Q.No.3. Answer any Three of the following Questions:                         (3 x 4 = 12)
     a) Compare Germanium and silicon as semi-conducting materials.
     b) Discuss the Hall effect phenomenon and give the area of
        application where this effect is made use of.
     c) Define the term ‘Thermistor’. Discuss in detail properties of
        Thermistor and possible application.
     d) Write a short note on LDR and LCD.

Q.No.4. Answer any two of the following Questions:                           (2 x 6 = 12)
     a) Discuss in detail polar and nonpolar materials.
     b) Explain the charging and discharging of a dielectric material.
        Also explain the term ‘permittivity’ of a dielectric material.
     c) Explain in detail the conduction through liquid dielectrics.

Q.No.5. Answer any two of the following Questions:                           (2 x 6 = 12)
     a) Give the general classification of insulating materials giving
        examples.
     b) Give the types of applications of insulating varnishes, paints and
        waxes.
     c) Discuss the properties and applications of PVC and ceramic as
        insulating materials used in electrical engineering.

                                                                                ………2/-
                                        -2-

Q.No.6. Answer any two of the following Questions:                            (2 x 6 = 12)
     a) i) Give the classification of magnetic materials according to their       (03)
            relative permeability and give examples of each.
        ii) State the properties required of a magnetic material used for        (03)
           1) Making transformer core and 2) making permanent magnets.
     b) i) Draw typical hysteresis loop for wrought iron and hard steel.         (03)
        ii) List out the properties of Tungsten and give its area of             (03)
            application.
     c) Explain the properties and uses of materials for i) Fuses                (06)
        ii) thermocouple.


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