Electrical Engineering Materials Question Paper of 3rd Semester Electrical(D) Download Previous Years Question Paper 13

S.B. Roll No.______

ELECTRICAL ENGINEERING MATERIALS

3^rd Exam/Elect/5206/May 10

Duration: 3 hrs.

1.     Fill in the blanks

a.     If a current of 100 mA  flows through a resistance of 100 . the power consumed in the resistance is ______.

b.     One kilowatt hour is 200 watts used for ________ hours.

c.      In order to calculate The venin resistance, voltage source is replaced by _______

d.     The unit of flux density is ________

e.      In a composite magnetic circuit, the total reluctance will _________ of individual parts.

f.        The energy stored in the magnetic field is __________

g.     A lead acid cell should not be discharged beyond _____________ volts.

h.     Wheat stone bridge is used to measure _________

i.       In a pure inductive circuit, the voltage will ______ the current by 90

j.       In two wattmeter method, when the point of the load is zero leading or lagging, the two wattmeter will give______ reading.

Section –B

Note: Attempt any five questions

2.       

a.     Explain Kirchhoff’s current law and Kirchhoff’s voltage law.

b.     Define resistance and what are the factors affecting and resistance of a conductor?

c.      Find the force per meter length between two conductors 0.05 m apart carrying 1000 A and 5000 A respectively.

d.     Explain self induced e.mf. and mutually induced e.m.f.

e.      What are the essentials of an electric cell? How the cell are classified?

f.       Explain the terms amplitude, cycle, time period, frequency and phase difference as applicable to alternation wave forms.

g.     Explain with mathematical expression that power consumed in a pure inductance is zero.

Section –C

Note: Attempt any three questions

3.     State and explain Norton’s theorem. Show that this theorem is just the converse of The venin’s theorem.

4.       

a.     Explain eddy current loss

b.     Give analog between electric and magnetic circuits.

5.     Explain constant current and constant voltage method of charging a battery.

6.     Explain constant current and constant voltage method of charging a battery.

7.     Derive an expression for the total power in balanced 3 phase load.

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Electrical Engineering Materials Question Paper of 3rd Semester Electrical(D) Download Previous Years Question Paper 12

S.B. Roll No.______

ELECTRICAL ENGINEERING MATERIALS

3^rd Exam/Elect/0152/May 10

Duration: 3 hrs.

1.     Fill in the blanks

a.     In conductors the temperature coefficient of resistance is _________

b.     The commercial unit of electrical energy is _______

c.      KOH electrolyte is used in _______

d.     Hennery is unit of _______

e.      In a pure ___________  circuit current leads voltage by 90̊

f.       ____________ is defined as the cosine of angle between voltage and current.

g.     ____________ power is measured in Var.

h.     The base of an _______ triangle represents resistance.

i.       In _________ type of connection I_L =I_pn

j.       Acceding to KCL, algebraic sum of all the currents meeting at a point is ________

Section –B

Note: Attempt any five questions

2.      

a.     State and explain Kirchhoff’s current law.

b.     With neat sketch explain the construction of silver oxide cell.

c.      Derive an expression for total inductance if two coils are joined in parallel considering both the cases of additive and subtractive fluxes.

d.     Differentiate between AC and DC in tabular form.

e.      Derive an expression for average value of current.

f.       Define power factor. What are the disadvantages of low power factor.

g.     What are the advantages of three phase system over single phase system.

h.     Define self inductance (L) and prove that L = N0/1

Section –C

3.     State and prove The venin’s theorem.

4.     Derive an expression  for energy stored n an inductor.

5.     What neat sketches explain the two different methods of charging of lead acid battery.

6.     Derive an expression for current, voltage and power consumed in a pure inductive circuit. Also draw and explain power curve.

7.     Three inductive coils of 0.05 H are connected in star to a 3 phase 200 volts,  50 Hz system. Calculate the inductance of 3 coils which when connected in delta to the same system, will take same line current.   

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Electrical Engineering Materials Question Paper of 3rd Semester Electrical(D) Download Previous Years Question Paper 11

S.B. Roll No.______

ELECTRICAL ENGINEERING MATERIALS

3^rd Exam/Elect/5206/May 06

Duration: 3 hrs.

1.     Fill in the blanks

a.     Temperature coefficient of a metal conductor increases with __________in temperature.

b.     A _________ cell is one that cannot be charged.

c.      E.M.F of cell is always ______ than its terminal voltage.

d.     While applying kickoffs laws direction of current flow may be assumed either clockwise or __________

e.      The unit of electric flux ___________

f.       Ferromagnetic materials lose their _______ property at a _____ known as curie point.

g.     When even flux linked with a circuit changes an ______ is always induced in it.

h.     The self –induction of a coil is also called its ________ inertia.

i.       The average valve of a symmetrical sinusoidal alternating current is ______

j.       In a series R-L circuit always _______ behind the applied voltage.

Section –B

          Note: Attempt any six questions

2.       

a.     How potential differences is maintained in an electric circuit.

b.     State and explain ohm’s law

c.      Two coil connected in series have a resistance of 18Ω and when connected in parallel have a resistance of 4 Ω. Find the resistance of the coil.

d.     Explain construction of lead acid battery.

e.      Derive an expression for the force acting between two parallel current carrying conductors.

f.       State and explain faraday’s laws of electromagnetic inductions.

g.     What do you mean by alternating voltage and current.

Section –C

3.     Explain care and maintenance of lead acid battery.

Or

Explain the following

a.     Lenz’s law

b.     Fleming’s right hand rule

4.     Define the following term as applied to alternating current:

a.     Wave form

b.     Instantaneous valve

c.      Frequency

d.     Amplitude

e.       R.M.S valve

Or

A coil having resistance of 5 Ω ohm and an inductance of 31.8 m H is connected across a 200 v 50 Hz supply calculate

a.     Current taken

b.     Power factor

c.      Power consumed

5.     Write the short note on any two

a.     Advantages of 3 phase over single phase system

b.     Power factor improvement

c.      Causes of low power factor

d.     Application of lead acid battery.  

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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.

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Electrical Engineering Materials Question Paper of 3rd Semester Electrical(D) Download Previous Years Question Paper 9

S.B. Roll No.______

ELECTRICAL ENGINEERING MATERIALS

3^rd Exam/Elect/5208/May’10

Duration: 3 hrs.

Section-A

1.     Fill in the blanks

a.     In insulators the temperature coefficient of resistance is _____

b.     Brass is an ________ of copper.

c.      The conductors are stranded to improve

d.     A rectifier converts ac into ______

e.      Varnishes are used for impregnation of _______

f.       PTFE stands for________

g.     Expansion of CRGO is _______

h.     The process of adding sulphur in rubber to make it hard is called _______

i.       By using thin laminations __________ losses are reduced.

j.       Humidity decreases the ________ of insulators.

Section –B

2.       

a.     How can we select three types of electrical engineering materials on the basis of band theory.

b.     Explain the various properties of low resistivity conducting materials.

c.      Write any three application of each

                                                             i.      Aluminum

                                                           ii.      Steel

d.     With neat sketch explain the working of P type semiconductor.

e.      Explain the various characteristics of sulphurhexfluoride gas used as insulator

f.       With neat figure explain the working of thermocouple.

g.     With figures explain the three different types of tungsten filaments

h.     Define magnetic flux density and magnetizing force and derive relation between them.

Section –C

Note: Attempt any three questions

3.     With phasor diagram derive an expression for dielectric loss of insulator.

4.     Resistance of a conductor is 80 ohms at zero degree C find its resistance at 100 degree C. if the temperature coefficient of material is 0.0043 at zero degree C.

5.     In tabular form differentiate between applications and character of soft and hard magnetic materials.

6.     Explain the various materials used for making core, winding, bushing and tank of transformer.

7.     Write short note on

a.     Superconductivity

b.     ACSR

c.      Eddy current loss

d.     Application of mica

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Electrical Engineering Materials Question Paper of 3rd Semester Electrical(D) Download Previous Years Question Paper 8

S.B. Roll No.______

ELECTRICAL ENGINEERING MATERIALS

3^rd Exam/EE/5208/May’08

Duration: 3 hrs.

1.     Fill in the blanks

a.     The electrical class fiction of materials is based upon _____

b.     Filament of lamps is made of _________

c.      Low resistivity materials have  __________ value of conductivity.

d.     In N- type semiconductors, the minority carriers are ______

e.      A pure semiconductor is called_______

f.       ___________ is employed for cable insulation.

g.     A good insulating materials should have ________ dielectric strength.

h.     Area of hysteresis loop ________

i.       Fuse is always connected in ______ with the electric and electronic circuit.

j.       The materials used for making brushes of a DC machine is made of _____

Section –B

2.     Attempt any six questions.

a.     Although silver is best known conductor, yet we prefer copper and aluminum, why?

b.     What is resistance? On what factors does it depend? How it is affected by temperature?

c.      Explain the effect of alloying on resistivity with examples.

d.     Why the temperature coefficient of resistance of a semiconductor is negative? Explain.

e.      Write down some important applications of following:

                                                             i.      Bakelite

                                                           ii.      PVC

f.       What are the various thermal properties of insulating materials?

g.     What are soft and hard magnetic materials?

h.     Fuse material should have low melting point, why?

Section –C

          Note: Attempt any three questions

3.      

a.     Explain the following terms:

                                                             i.      Valence electrons

                                                           ii.      Band gap

b.     What are superconducting materials?

4.       

a.     What are the major alloys of copper?

b.     Differentiate between intrinsic and extrinsic semiconductors.

5.     Mention a few applications of the following natural insulating materials:

a.     Mica

b.     Asbestos

c.      Cotton

d.     Porcelain

6.     Write the short note on

a.     Thermosetting plastics

b.     Magnetisteictan 

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Electrical Engineering Materials Question Paper of 3rd Semester Electrical(D) Download Previous Years Question Paper 7

B. Roll No.______

ELECTRICAL ENGINEERING MATERIALS

3^rd Exam/Elect/5243/May’06

Duration: 3 hrs.

1.     Choose the correct one

a.     Resistivity of metals is expressed in terms of

                                                             i.      µ Ohm

                                                           ii.      µ Ohm/cm

                                                        iii.      µ Ohm

                                                        iv.      µ Ohm-cm/̊C

b.     thermocouple works on which of the following effects.

                                                             i.      Thomson effect

                                                           ii.      Seeback effect

                                                        iii.      Peltier effect

                                                        iv.      Joule effect

c.      When a ferromagnetic substance is magnetized small changes in dimensions occur. Such a phenomenon is known as

                                                             i.      Magnetic hysteresis

                                                           ii.      Magnetic expansion

                                                        iii.      Magnetostriction

                                                        iv.       Magneto- colorization

d.     Which of the following properties has lower value for copper as compared to aluminum?

                                                             i.      Specific gravity

                                                           ii.      Melting point

                                                        iii.      Resistivity

                                                        iv.      All of the above

e.      Soft magnetic materials are widely used in

                                                             i.      Meters

                                                           ii.      Transducers

                                                        iii.      Transformer cores

                                                        iv.      Televisions

State true or false

i.       Ferrites are generally hard and brittle

j.       Aluminum is easily soldrable

k.      Age hardening increases the resistivity of an alloy.

l.       The crystal structure of silicon is diamond.

m.  Bronze is an alloy of copper zinc and tin.

Section –B

Note: attempt any five questions

2.              

a.     Explain in the following terms:

                                                             i.      Valence band

                                                           ii.      Conduction band

b.     What is superconductivity? Explain.

c.      Explain the following:

                                                             i.      Dielectric loss

                                                           ii.      Dielectric strength

d.     What do you mean by volume resistivity? Explain

e.      What are different applications  of semi conducting materials?

f.       What do you mean by Magnetostrication in ferromagnetic material? Explain  

g.     Discuss the properties of Bakelite.

                                                             i.      What do you mean by permeability? Explain

                                                           ii.      Define abrasion resistance

Section –C

Note: Attempt any three questions

3.     What do you mean by resistivity? Explain the factor affecting resitivity.

4.     Discuss properties and applications of following material

a.     Air

b.     Bitumen

5.     Explain properties and applications of following soft magnetic materials

a.     Nickel iron alloy

b.     Soft ferrites

6.     Write the short note on

a.     Thermoplastic

b.     Thermocouple

7.     Explain properties and application of following materials

a.     Steel

b.     Polyvinyl chloride

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