Electrical Engineering Materials Question Paper of 3rd Semester Electrical(D) Download Previous Years Question Paper 10

B. Roll No.______

ELECTRICAL ENGINEERING MATERIALS

3^rd Exam/Elect/5243/Dec 03

Duration: 3 hrs.

Note: Attempt any five questions

1.      

a.     Explain what do you understand by fuse materials. Explain with the help of a neat sketch the cartridge fuse.

b.     Explain the solcers and flux used in Aluminum cable jointing. State with reasons the material used for the following:

                                                             i.      Storage Battery plate

                                                           ii.      Bimetal

2.       

a.     Explain with the help of energy diagram the N –type and the P-type semiconductors. Explain brief the hall effect.

b.     Mention the type of current carriers available in semiconductors at absolute zero temperature. Out of the following atoms state the types of impurity (P or N ) they are used as:

                                                             i.      Zinc

                                                           ii.      Barium

                                                        iii.      Sulphur

                                                        iv.      Gallium

                                                           v.      Carbon

3.              

a.     Explain how covalent bond is formed with the sharing of free electrons. Explain the types of interatormic bond found in the following:

                                                             i.      Solid insulating materials.

                                                           ii.      Ductile and high conductivity materials

b.      Explain the conduction process case of:

                                                             i.      Conductors

                                                           ii.      Semiconductors

Name the commonly used semiconductors materials and explain the effect of mixing of impurity on the conductivity.

4.       

a.     Explain the difference between dielectric material and insulating materials. Explain the polarization process of a dielectric material and also explain the physical concept of dielectric loss.

b.     Explain the following

                                                             i.      Permeability

                                                           ii.      Breakdown voltage

                                                        iii.      Dialectic strength

                                                        iv.      Permittivity

5.       

a.     State the characteristics of an ideal dielectric. Which insulating material will you select for the following? Give reasons:

                                                             i.      Flexible wire

                                                           ii.      Commutator in dc machines   

                                                        iii.      Cable jointing box

b.     Mention the factors which effect the dielectric loss of insulating materials.

Explain with the help of phasor diagram

                                                             i.      Dielectric loss,

                                                           ii.      Loss angle.

6.      

a.     Explain ‘Superconductity’. Mention few names of superconductors and their applications. Compare the merits and demerits of copper and Aluminum on the basis of their properties and applications.  

b.     Name few alloy which are used as conducting materials. Explain why these alloys are sued inspite their higher values of resistivity as compared to pre metals. Explain why copper and aluminum are not used for manufacturing heater elements. 

7.       

a.     Explain how the magnetic materials are classified. Compare the hysteresis loop of a soft magnetic material to that of a hard magnetic material.

b.     Differentiate between the requirements of the magnetic materials used for

                                                             i.      Communication applications

                                                           ii.      Power applications. Describe the soft ferrites in brief and explain its most important applications.

8.     Write short notes on any three of the following:

a.     Thermocouple and their applications

b.     Gaseous material and their applications

c.      Non electrical Engineering materials and their applications. 

d.     Hard  magnetic materials and their applications.

e.      Natural insulating materials and their applications.