QUESTION BANK FOR ENGINEERING PHYSICS -II REGULATION 2013

7/24/2019 QUESTION BANK FOR ENGINEERING PHYSICS -II REGULATION 2013

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PH6251 ENGINEERING PHYSICS -II

UNIT 1 CONDUCTING MATERIALS

PART A

1 Give any three postulates of classical free electron theory.

2 Define drift velocity. How is it different from thermal velocity of an

electron?

3 Define the terms relaxation time, collision time and Mean free path of

an electron.

Define !lectrical resistivity. "rite its unit.

# $he mo%ility of electron in copper is 3x1&'3

m2()s. *ssumin+ e

1.-x1&'1

/ and me .1x1&'31

0+, calculate the Mean free time.

- Differentiate %etween electrical conductivity and thermal conductivity.

Mention the draw%ac0s of classical free electron theory of metals.

"hat are the merits of classical free electron theory of metals.

ind the drift velocity of electrons copper wire whose cross sectional

area is 1 mm2. "hen the wire carries a current of 1& *. *ssume that

each copper atom contri%utes one electron of the electron +as. Given n

.#x1&2

(m3

1& * conductin+ rod contains .#x1&2

electrons per m3. /alculate the

electrical conductivity at room temperature if the collision time for

electron is 2 4 1&'1 s.

11 5tate any three assumptions of 6uantum free electron theory.

12 "hat are the merits and demerits of 6uantum free electron theory?

13 Define ermi level and ermi !ner+y with its importance.

1 "rite down the expression for ermi'Dirac distri%ution function and

plot it as a function of ener+y.1# /alculate the ermi ener+y of copper at &

78 if the concentration of

electrons is .#x1&2

m'3

1- "hy we have ener+y %ands in solids and ener+y levels in +ases.

1 Define 9orent: num%er

1 $he thermal conductivity of a metal is 123.2 "(m(0 . ind the

electrical conductivity and 9orent: num%er when the metal possess

relaxation time 1&'1

seconds and 3&& 8.;Density of electrons - x 1&2

(m3


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2& $he ermi level for potassium is 2.1e). calculate the velocity of

electrons at the ermi level.

PART B

1 i< Define !lectrical conductivity. Derive an expression for electricalconductivity of a metal %y usin+ classical free electron theory.ii< ind the mo%ility of electrons in copper if there are x1&

2valence

electrons(m3and the conductivity of copper is -x1&

mho(m

2 i< Define thermal conductivity Derive an expression for thermal conductivity

of a metal.

ii< /alculate the electrical and thermal conductivities for a metal with a

relaxation time 1&'1

second at 3&& 8. *lso calculate 9orent: num%er usin+

the a%ove result. ;density of electrons -x1&2

m'3


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relaxation time of 1&'1

second at 3&& 8. $he electron density is -x1&2-

m'3

.

iii


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1 Derive an expression for density of electrons in theconduction %and and density of holes in the valence %and in

an intrinsic semiconductor.2 Derive the intrinsic carrier concentration for intrinsic

semiconductor and also calculate the ermi level and its

variation with temperature.3 i


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a succepti%ility of 1&&&. /alculate the ;i< ntensity of

Ma+netisation and ;ii< lux density

- Define ma+netic succepti%ility and permea%ility.

* ma+netic field of 1&& ampere(metre produces a ma+netic flux

of 3x1&'#

we%er in an iron %ar of cross sectional area &.2 cm2.

/alculate permea%ility. Define retentivity and coercivity.

"hat is hysteresis loop? "hat do you infer from it?

1& Distin+uish erro and anti erroma+netic materials.

11 Define superconductivity.

12Mention the condition for the material to %ehave as a

superconductor.

13Define critical temperature and critical field.

1 "hat is isotope effect?

1# "hat is meant %y persistent current?

1- "hat are cryotron switches?

1 Define cooper pairs.

1 How can you chan+e a superconductor from $ype to $ype

/alculate the critical current for a wire of lead havin+ a diameter

1of 1mm at .2 8. /ritical temperature for lead is .1 8 and H&

-.#x1&*(m.

$he critical temperature for H+ with isotopic mass 1.# at .1

2&8. /alculate the critical temperature when its mass chan+es to

2&3..

PART-B

i


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iii< * +iven material has a suscepti%ility of &&. Determine the relative

permea%ility of the material.

i< /ompare soft and hard ma+netic materials.

ii< ron has relative permea%ility of #&&&. /alculate its ma+netic

suscepti%ility.

iii< "hat is antiferroma+netism? Give examples. Mention its

characteristics

i< "hat are ferrites? !xplain the structure of ferrites, properties and its

#applications.

ii< "hy are errites advanta+es for use as transformer core.

- !xplain the different properties of superconductors in detail.

i< "hat is Meissner effect? =rove that all superconductors are perfect

dia'ma+net in superconductin+ state

ii< Discuss the important features and the prediction of A/5 theory.

i< Differentiate the $ype and $ype superconductors

ii< "rite an essay on Hi+h temperature superconductors.

i< Discuss the applications of superconductors in detail.

ii< 5uperconductin+ tin has a critical temperature of 3. 8 at :ero

ma+netic field and a critical field of &.&3&- tesla at & 8. ind thecritical field at 2 8.

!xplain the followin+ in detail

1& i< */ and D/ Cosephson !ffect ii< 5ID

ii< /ryotron iv< Ma+netic 9evitation

UNIT - I( Die&et$i Mate$ia&'

PART- A

S)N% *"e'ti%n'1 Descri%e the definition of Dielectrics.

2 Distin+uish 9orent: and /oloum% force in Dielectrics.

3 Define electric polari:ation and electric suscepti%ility.

Distin+uish %etween active and passive dielectrics.

# Define dielectric constant.

- Define the relaxation fre6uency in dielectrics.

Define space char+e polari:ation.

6


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5ummari:e the types of polari:ation mechanism involved in

dielectric material.

Differentiate dielectric loss and dielectric %rea0down.

1& Generalise the re6uirements of a +ood insulatin+ materials.

115how that the electronic polari:a%ility for a monoatomic

+asincreases as the si:e of the +as increases.

$he polari:a%ility of 0rypton atom is 2.1 x1&'&

m2./alculate

12 its dielectric constant at &&/ and 1 atmosphere.the num%er of

0rypton atoms at B$= is 2.- x 1&2#

( m3.

13Define dipole moment and classify dielectric materials on its

%asis.

1 !xplain polar and non polar dielectrics.

/alculate the polari:ation produced in a dielectric medium of

1# dielectric constant - and it is su%@ected to an electric field of 1&&

)(m. Given & .# x 1&'12

(m.

1- 9ist the factors affectin+ dielectric loss in a dielectric materials.

1 *nalysi:e the properties of ferroelectric materials.

*n atom has a polari:i%ility of 1&'&

m'2

.t finds itself at a

1 distance of 1.& nm from proton. /alculate the dipole moment

induced in the atom ;& .# x 1&'12

(m


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polari:ation in dielectrics.

"hat is meant %y local field in a dielectric? *nd how it is

# calculated for a cu%ic structure? Deduce the /lausius J Mosotti

relation.

i< $he relative dielectric constant of sulphur is 3.# when

measured at 2&/.*ssumin+ the internal field 1(3, /alculate the

electronic polari:a%ility of sulphur if its density at this

-temperature is 2&0+(m

3. $he atomic wei+ht of sulphur %ein+ 32.

ii< * capacitor consists of two conductin+ plates of area 2&& cm2

each separated %y a dielectric constant 3. of thic0ness 1mm.

ind the capacitance and the electric flux density when a

potential of 3&& ) is applied. ;& .# x 1&'12

(m


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11 Differentiate one'way and two'way shape memory alloys?

12 Mention the advanta+es and disadvanta+es of shape memory alloys.

13 "hat are nanophase materials? Give examples.

1 5tate few techni6ues for synthesis of nano phased materials.

1# !xplain top down and %ottom up approach in nano materials?

1- Give any four non'linear optical properties.

1 "hat is meant %y second harmonic +eneration?

1 "hat are %io'materials?

1 /lassify the types of %io'materials?

2& "hat are the applications of %iomaterials?

PART-B

S)N% *"e'ti%n'1 "hat are metallic +lasses? Descri%e the preparation and properties

and applications of metallic +lasses.2 How are metallic +lasses prepared? !xplain how the melt spinner

device can %e used to produce met +lasses.3 !xplain the properties and application of metallic +lasses also

mention its types with examples "hat are shape memory alloys? Descri%e the characteristics of

5M* and its applications?

i< Mention the properties of Bi J$i alloy.

#ii< !xplain the applications of 5M*

iii< !xplain the advanta+es and disadvanta+es of 5M*.

- "hat are nanomaterials. !xplain the preparation, properties and

applications nanomaterials.

Descri%e the method of producin+ nano materials usin+

=ulsed laser deposition

/hemical vapour deposition.

i< !xplain Airefrin+enceii< !xplain optical 8err effect.

iii< !xplain non'linear materials. Give examples !xplain the ori+in of non'linear optics? How are second harmonic

wave +enerated

1& !xplain %iomaterials, classification and its modern application in

field of medicine

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QUESTION BANK FOR ENGINEERING PHYSICS -II REGULATION 2013