Electrical Engineering Materials Question Paper of 3rd Semester Electrical(D) Download Previous Years Question Paper 6

S.B. Roll No.______

ELECTRICAL ENGINEERING MATERIALS

3^rd Exam/Elect/5243/May’08

Duration: 3 hrs.

Note: Attempt any five questions. Question no. 1 is compulsory

1.     Fill in the blanks

a.     The atoms in which the outermost orbit is complete with elght electrons in it are stable and _______

b.     Galvanized _________ wires are used as over head telephone wires and as earth wires

c.      Carbon has a ________ temperature coefficient of resistance.

d.     Rise in  temperature _________ the oxidation of liquid insulating materials.

e.      Grain oriented of silicon steel is obtained by a special manufacturing process called _________

f.       Bimetal relays are used for _________ protection of electric motors.

g.     For ordinary soldering _________ is common flux.

h.     Dielectric strength of an insulating material is express in __________

i.       The core of dynamo is fabricated of _________ material.

2.       

a.     Explain the energy band diagram of conducting, semi conducting and insulating materials

b.     What is super conductivity? Give its important applications.

3.       

a.     Explain the selection procedure of conducting material used in electrical machines.

b.     Give reasons, why ACSR conductors are used in power lines.

c.      What is galvanized and mention its applications in electrical engineering

4.       

a.     Give the properties of materials used in making electrical contacts.

b.     What is semiconductor and compare Ge and Si when used as a semi conductors?

c.      Explain the laws of resistance?

A heater element is made of nicrome wire having resistively equal to 100 x 10^-8 ohm meter. The dia of the wire is 0.4 calculate the length of wire required to get resistance of 50Ω and 1000 watts.

5.      

a.     Discuss the dielectric loss and dielectric constant?

b.     Explain the physical properties of insulators?

c.       Give the important properties and application of polyethylene?

6.       

a.     Give reasons why poreelin is used in making insulators of power lines?

b.     Give reasons why hydrogen gas is used in rotating electrical machines?

c.       What is vulcanization ? give reasons why rubber is vulcanized?

7.       

a.     Explain the magnetization curve with neat diagram?

b.     Give reasons , why high silicon steel is used in transformers cores?

c.      Give the important properties and applications of tungsten steel?

8.       

a.     What is thermocouple and where thermocouples are used?

b.     Discuss , how the structural material of electrical machines is fabricated?

c.      Give the important properties of conducting material used in making solders and mention the need of flux in soldering ?