PART – A
UNIT- I
CONDUCTING MATERIALS
1. Define mobility give its unit.
Mobility (µ):
Mobility is defined as the drift velocity acquired by the free electrons per unit electric
field (E) applied to it.
µ=
Unit is m2/V.sec
2. Define Drift velocity.
The average velocity acquired by the free electron in a particular direction due to the
application of electric field is called as Drift velocity.
3. What are the drawbacks of classical free electron theory?

It is a macroscopic theory.

According to this theory, K/sT = L, a constant (Wiedemann-Franz law) for all
temperatures. But this is not true at low temperatures.

The theoretically predicted value of specific heat of a metal does not agree with the
experimentally obtained value.

This theory fails to explain ferromagnetism, superconductivity, photoelectric effect,
Compton Effect and black body radiation.

It is a macroscopic theory.

Dual nature is not explained and atomic fine spectra could not be accounted.
4. Define Mean free path.
The average distance travelled between two successive collisions is called mean free
path.
(i.e) λ = τc, where is the root mean square velocity of the electron.
5. Define Collision Time.
Collision time (τc):
It is the average time taken by the free electron between two successive collision.
τ=
Where, λ is the mean free path.
6. Define Electrical Conductivity.
Electrical conductivity which is defined as the quantity of electricity flowing per unit
area per unit time maintained at unit potential gradient. Unit is Ω-1m-1
σ =
7. Define Thermal Conductivity.
Thermal conductivity of the material is defined as the amount of heat conducted per unit
area per unit time maintained at unit temperature gradient. Unit Wm-1K-1
8. State Wiedemann-Franz law.
Wiedemann – Franz Law
The ratio between the thermal conductivity and electrical conductivity of a metal is
directly proportional to the absolute temperature of the metal.
(i.e)
Where, L is a constant called as Lorentz number whose value is 2.44 x
2
WΩK-
(Quantum mechanical value) at temperature T = 293 K.
9. Define Lorentz number.
The ratio between the thermal conductivity and the product of absolute temperature and
electrical conductivity is called Lorentz number.
10. Define relaxation time of an electron.
It is the time taken by the free electron to reach its equilibrium position from its
disturbed position in the presence of applied field.
τ=
Where, l is the distance travelled by the electron
11. Write Fermi-Dirac distribution formula.
F (E ) =
Where EF is the Fermi energy
KB is the Boltzmann constant
12. Define Fermi level and Fermi Energy with its importance.
Fermi energy level is the maximum energy level upto which the electrons can be filled
at 0K.
Importance:
1. Fermi energy level act as a reference level which seperates the vacant and filled states at
0K.
2. It gives the information about the filled electron states and the empty states.
3. At 0K, below Fermi energy level electrons are filled at above Fermi energy level it will
be empty.
4. When the temperature is increased, few electron gains the thermal energy and it goes to
higher energy levels.
13. How does Fermi function varies with temperature
(i) At 0 kelvin
At 0 kelvin, the electrons can be filled only upto a maximum energy level called Fermi
energy (
), above
all the energy levels will be empty. It can be proved from the following
conditions.
(i) When E< EF F(E ) =
= =1
[ i.e., 100% chance for the electron to be filled within the Fermi energy level]
(ii) When E>EF, equation ( 1 ) becomes,
F(E ) =
=
=0
[i.e Zero % chance for the electron not to be filled within the Fermi energy level]
(iii) When E=EF, equation ( 1 ) becomes,
F(E ) =
= = 0.5
[i.e 50% chance for the electron to be filled and not to be filled within the Fermi energy level]
(ii) At any temperatue T kelvin:
When the temperature is raised slowly from absolute zero, the Fermi distribution
function smoothly decreases to zero as shown in fig.
14. Define density of states.
Density of States Z (E) dE is defined as the number of available energy states per unit
volume in an energy interval.(dE).
15. Mention the advantages of classical free electron theory

It verifies Ohm’s law.

It explains the electrical and thermal conductivity of metals.

It is used to derive Wiedemann-Franz law.

The optical properties of metals can be explained using this theory
16. Define Fermi function.
Fermi distribution function F (E) represents the probability of an electron occupying a
given energy state.
17. List out the types of free electron theory.

Classical Free electron theory

Quantum Free electron theory

Brillouin Zone theory or Band theory
UNIT- II
SEMI CONDUCTORS MATERIALS
1.
What are compound semiconductors?
Give examples.
Compound Semiconductors
The Compound Semiconductors are made by combining the third and fifth column
elements (or) second sixth column elements. GaAs, GaSb, InP, are the important examples for
Compound Semiconductors.
2.
What is an intrinsic-semiconductor?
Intrinsic semiconductor
A semiconductor in a extremely pure form is called as intrinsic semiconductors.
Ex. Germanium and silicon
3. What is an extrinsic-semiconductor?
Extrinsic semiconductor
Impure semiconductors in which the charge carriers are produced due to impurity atoms
are called extrinsic semiconductor. they are obtained by doping an intrinsic semiconductor with
impurity atoms.
Based on the type of impurity added they are classified into

n-type semiconductor

P-type semiconductor
4. What is an N-type semi-conductor? Give example.
An intrinsic semiconductor doped with pentavalent (electrons in valence band) impurity
atoms like phosphorus, arsenic, antimony, etc., is called N-type semiconductor.
Ex:
5. What is P-type semi-conductor? Give example.
An intrinsic semiconductor doped with trivalent impurity atoms like boron, Gallium,
Indium, etc., is called P-type semiconductor.
Ex:
6.
What is Hall effect?
When a conductor (metal or semiconductor) carrying a current is placed in a transverse
magnectic field, an electric field is produced inside the conductor in a direction normal to both
the current and the magnectic field. This phenomenon is known as Hall effect.
UNIT-3
MAGNETIC AND SUPERCONDUCTING MATERIALS
1. What is magnetic material?
Magnetic materials are the materials which can be made to behave as magnets. When
these materials are kept in an external magnetic field, they will create a permanent magnetic
moment in it. Ex: Diamagnetic, Paramagnetic, Ferromagnetic, Antiferromagnetic and
Ferromagnetic materials.
2. Define magnetic Induction give its unit
It is defined as the number of magnetic lines of force passing normally through unit area
of cross section at that point.
3. Define magnetic field Intensity give its unit
Magnetic field intensity (H)
It is defined as the force experienced by a unit North Pole placed at the given point in a
magnetic field.
4. Define Magnetic permeability
Magnetic permeability (µ)
It is defined as the ratio between the magnetic flux density (B) and the magnetic field
intensity (H)
µ=
5. Define relative permeability
6. Define Intensity of magnetization
Magnetisation (or) Intensity of Magnetisation (I)
The magnetization is the process of converting a non-magnetic material into a magnetic
material. It measures the magnetization of the magnetized specimen. It also defined as the
magnetic moment per unit volume
7. What is magnetic susceptibility
Magnetic susceptibility (χm)
It is defined as the ratio between intensity of magnetization (I) and the magnetic field
intensity (H)
χm =
8. State any four properties of Dia magnetic substance
1. They repel the magnetic lines of force
2. Susceptibility is negative and it is independent of temperature and applied magnetic
field strength
3. Permeability is less than 1
4. There is no permanent dipole moment, so they are called weak magnets
9. State any four properties of Para magnetic substance
a. The magnetic lines of force pass through the material
b. Magnetic susceptibility is positive and it is given by
c. Permeability is greater than one
d. They possess permanent dipole moment
10. State any four properties of Ferro magnetic substance
a. Since some magnetization is already existing in these materials, all the magnetic lines of
force passes through it
b. They have permanent dipole moment. So they act as strong magnets.
c. They exhibit magnetization even in the absence of external field. This property is called
Spontaneous magnetization.
d. Its susceptibility is positive and high and it is given by
e. When the temperature is greater than Curie temperature, ferromagnetic material
becomes paramagnetic material.
f. Permeability is very much greater than 1
11. What is Curie temperature?
Curie temperature is the critical temperature below which a materials can behaves as ferromagnetic
material and above which it can behaves as paramagnetic materials.
12. Define Bohr magnetron
Bohr Magneton
The total magnetic moment and the spin magnetic moment of an electron in an atom
can be expressed in terms of atomic unit of magnetic moment called Bohr magneton.
1 Bohr magneton = eħ/2m = 9.27 x 10-24 Am2
13. Define Magnetic moment
Magnetic dipole moment
A system having two opposite magnetic poles separated by a distance‘d’ is called as a
magnetic dipole. If ‘m’ is magnetic pole strength and ‘l’ is the length of the magnet, then its
dipole moment is given by
M = ml
Magnetic moment can also be defined as M = ia, where i is the electric current that
flows through a circular wire of an area of cross section ‘a’.
14. Define Hysteresis
When a ferromagnetic material is made to undergo through a cycle of magnetization,
the variation of B with respect to H can be represented by a closed hysteresis
15. Distinguish between hard magnetic materials and soft magnetic material.
1
They have large hysteresis loss due to
They have low hysteresis loss due to small
large hysteresis loop area.
hysteresis area.
2 Susceptibility and permeability are low.
3
Coercivity and retentivity values are
large.
Susceptibility and permeability are high.
Coercivity and retentivity values are less.
Since they have low retentivity and coercivity,
4 Magnetic energy stored is high.
they are not used for making permanent
magnets.
16. Define Transition temperature
The temperature at which a normal conductor loses its resistivity and becomes a super
conductor is known as transition temperature (or) Critical Temperature (Tc)
17. Define Super conductivity
The electrical resistance of pure mercury suddenly drops to zero, when it is cooled below
402 kelvin and becomes a super conductor. This phenomenon of losing the resistivity
absolutely, when cooled to sufficiently low temperature is called Super Conductivity.
18. Distinguish between Type-I and Type-II superconductor
Type I (soft) super conductor
When the super conductor is kept in the magnetic field and if the field is increased the super
conductor becomes a normal conductor abruptly at critical magnetic field as shown in figure. This
type of materials is termed as Type I superconductors.
19.
Below critical field, the specimen excludes all the magnetic lines of force and exhibits perfect
Meissner effect. Hence Type I super conductors are perfect diamagnets, represented by the
negative sign in magnetization.
Type II (hard) super conductor
When the super conductor is kept in the magnetic field and if the field is increased, below the
lower critical filed Hc1, the material exhibits perfect diamagnetism (i.e.,) it behaves as a
superconductor and above Hc1, the magnetization decreases and hence the magnetic flux starts
penetrating through the material. The specimen is said to be in a mixed state between Hc1 and Hc2.
Above Hc2 (upper critical field) it becomes a normal conductor as shown in figure.
20.
The material which loses its super conducting property gradually due to the increase in
magnetic field is called Type II (hard) super conductors.
21. What is Meissner Effect?
Meissner effect
When the super conducting material is placed in magnetic field, under the condition when T ≤
TC and H ≤ HC the flux lines are excluded from the material. Thus the material exhibits perfect
diamagnetism. This phenomenon is called as Meissner effect.
22. Define Isotope effect
Isotope effect
The transition temperature varies due to presence of isotopes.
Example
The atomic mass of mercury varies from 199.5 to 203.4, and hence the transition
temperature varies from 4.185 K to 4.146 K.
Due to the relationship (i.e.,)
[Tc α 1/Mα]
Where, M = atomic weight, α = constant (≈0.5)
23. What is high temperature superconductor? give example
High temperature super conductors are the materials which have transition temperature
Tc>100K. Usually in high temperature super conductors, the charge carriers are holes. Here,
crossing the transition temperature of 77K is important, because cooling can be accomplished
by liquid Nitrogen instead of liquid Helium, whose cost is more than Nitrogen. The rapid
increase of Tc leads to the discovery of La-Sr-Nb-O system, whose Tc is 255K. Super
conductors at room temperature are yet to be developed in future.
Examples
1. BaPb0.75Bi0.25O3 (BPBO) for this the transition temperature is Tc = 12K
2. La1.85Ba0.15CuO4 (LBCO) for this the transition temperature is Tc = 36K
24. What is SQUIDS?
SQUIDS (Super conducting Quantum Interference devices) are the improved model of
Josephson devices. It has high efficiency, sensitivity and quick performance.
Principle : Small change in magnetic field, produces variation in the flux quantum.
25. What is magnetic levitation?
Magnetic levitated train is the train which cannot move over the rail, rather it floats
above the rails, under the condition, when it moves faster.
Principle: Electro-magnetic induction is used as the principle (i.e.,) when there is a relative
motion of a conductor across the magnetic field, current is induced in the conductor and vice
versa.
26. How are different magnetic materials classified?
Classification of Magnetic
Materials
Having permanent
magnetic moment
Not having permanent
magnet moment
Paramagnetic
material
Diamagnetic material
Ferromagnetic
material
Ferrimagnetic
materia l
27. What is meant by Hysteresis loss?
Hysteresis loss
It is the loss of energy in taking a ferromagnetic specimen through a complete cycle of
magnetization and the area enclosed is called hysteresis loop.
28. Define Energy product of magnetic material.
A product of retentivity (Br) and coercivity (Hc) is made and this product is called energy
product, which gives the maximum amount of energy stored in the specimen is called energy
product.
29. What are the applications of ferrites?

They are used to produce ultrasonincs by magneto-striction principle.

Ferrites are used in audio and video transformers.

Ferrites rods are used in radio receivers to increase the sensitivity.

Since the ferrites have low hysteresis loss and eddy current loss, they are used in two
port devices such as gyrator, circulator and isolator.
Gyrator: It transmits the power freely in both directions with a phase shift of π radians.
Circulator: It provides sequential transmission of power between the ports.
Isolator: It is used to display differential attenuation.
UNIT IV
DIELECTRIC MATERIALS
1. Define electric polarization
The process of producing electric dipoles inside the dielectrics by an external electric field is called
electric polarization.
2. Compare active and passive dielectrics
Active Dielectrics
Dielectrics which can be easily adapt itself to store the electrical energy in it is called active
dielectrics. Ex: Piezo electrics, Ferro electrics, Pyro electrics.
It is used in production of Ultrasonics.
Passive Dielectrics
Dielectrics which restrict the flow of electrical energy in it are called passive dielectrics.
Ex: Glass, mica, plastic
It is used in production of sheets, pipes etc.
3. Define electronic polarization.
Due to the displacement of positively charged nucleus and negatively charged electrons in opposite
directions, when an external electric field is applied and thereby creates a dipole moment in the
dielectric is called Electronic polarization
4. Define local field.
When a dielectric material is kept in an external field it exerts a dipole moment in it. Therefore two
fields are exerted, viz.,
I.
II.
Due to external field
Due to dipole moment.
This long range of coulomb forces which is created due to the dipoles is called as internal field or
local field.
5. What is meant by dielectric loss and loss tangent? Why it occurs.
If a dielectric is subjected to an electric field, the electrical energy is absorbed by the dielectric and
certain quantity of electrical energy is dissipated in the form of heat energy. This is known as dielectric
loss.
The power loss
, where
is called loss tangent.
This dielectric loss mainly occurs due to the imaginary part of complex dielectric constant.
6. What is meant by dielectric breakdown and dielectric strength?
When a dielectric is placed in an electric field and if the electric field is increased, when the field
exceeds the critical field, the dielectric loses its insulating property and becomes conducting i.e., large
amount of current flows through it. This phenomenon is called dielectric breakdown.
The electric field strength at which the dielectric breakdown occurs is known as dielectric
strength.
The dielectric strength =Dielectric voltage/Thickness of dielectric
7. Explain electrochemical breakdown in dielectric.
Chemical and Electrochemical Breakdown
This type of breakdown is almost similar to the thermal breakdown. If the temperature is
increased mobility of the ions will increase and hence the electrochemical reaction may be induced to
take place.
Therefore when mobility of ions are increased, insulation resistance decreases and hence
dielectrics become conducting. This type of breakdown is called as chemical and electro chemical
breakdown.
Characteristics

It occurs only at low temperatures.

It occurs even in the absence of electric field. In rubber, due to oxides produced in air, they
gradually lose their dielectric property.

It depends on concentration of ions, magnitude of leakage current.
8. What are dielectric materials?
Dielectrics are non-metallic materials of high specific resistance ρ, negative temperature coefficient
of resistance (-α) and large insulation resistance. Insulation resistance will be affected by moisture,
temperature, applied field and age of dielectrics.
9. Define dielectric constant
Dielectric constant (ε r) is the measure of the polarization produced in the material. It is the ratio
between absolute permittivity (ε) and the permittivity of free space (ε 0).
i.e.,
10. Define polarization vector and electric displacement vector.
The polarization vector is defined as dipole moment per unit volume of the dielectric material.
A quantity which is used for analyzing electrostatic fields in the presence of dielectrics is called
Electric Displacement Vector or electric induction.
11. Define Ionic polarization.
Ionic polarization is defined as the displacement of cations (+ve ions) and anions (- ve ions) from
its original position, in opposite directions in the presence of electric field.
12. Define Space charge polarization
The space-charge polarization is defined as the diffusion of ions, along the field direction and
giving rise to redistribution of charges in the dielectrics.
13. Define orientation polarization.
The orientation polarization is defined as the presence of polar molecule in the dielectric
medium. When a dielectric which consists of polar molecules is kept in an electric field, the molecules
align themselves along the field direction. So there is a resultant dipole moment along the field
direction.
14. What is effect of frequency of an a.c field on polarization?
In general, the polarization decreases with the increase in frequency. At optical frequencies
electronic polarization is present and in infrared frequencies the ionic polarization occurs. The
orientation and space charge polarization will be absent at optical frequencies and will occur only
at radio and audio frequencies.
15. What is the effect of temperature on polarization?
The electronic and ionic polarizations are independent of temperature, whereas the orientation and
space charge polarizations are temperature dependent.
The orientation polarization decreases with increase in temperature because the randomizing action
of thermal energy decreases the tendency of the permanent dipoles to align the field direction. Hence
in this case the
decreases.
But in space charge polarization, when the temperature is increased, the ions can easily overcome
the activation barrier and hence they diffused through inter atomic distances. Thus it gives rise to
polarization. So in this case the
will increase in temperature.
16. What are the different breaks down mechanisms that occur in a dielectric material?

Intrinsic (or) avalanche breakdown

Thermal breakdown

Chemical and electrochemical breakdown

Discharge breakdown

Defect breakdown
17. Discuss the discharge and defect breakdown in dielectrics.
Discharge Breakdown
In some dielectric occluded gas bubbles may be present. When these type of dielectrics are
subjected to electric field, the gas present in the material will easily ionize and hence produce large
ionization current and is known as discharge breakdown.
Characteristics

It occurs at low voltages.

It occurs due to the presence of occluded gas bubbles.

It depends upon the frequency of the applied voltage.
Defect Breakdown
Some dielectrics have defects such as cracks, pores, blow holes etc. These vacant position may
have moisture (or) impurities which leads to breakdown called as defect breakdown.
18. What are the ways in which the dielectric breakdown can be minimized?

To avoid breakdown, the dielectric material should have the following properties.

It should have high resistivity.

It must posses high dielectric strength.

It should have sufficient mechanical strength.

Dielectric loss should be low.

Thermal expansion should be small.

It should be fire proof.
19. Give any four applications of dielectric in transformer.

Ceramics and polymers are used as insulators.

Paper, rubber, plastics, waxes etc are used to form thin films, sheet tapes, rods etc.

PVC (Poly Vinyl Chloride) is used to manufacture pipes, batteries, cables etc.

Glass, mica, asbestos, alumina are used in ceramics.
20. Write any four applications of dielectrics in capacitors.

Thin sheets of papers filled with synthetic oils are used as dielectrics in the capacitors.

Tissue papers and polypropylene flims filled with dielectrol are used in power capacitors.

Mica is used as dielectrics in discrete capacitors.

An electrolytic solution of sodium phosphate is used in wet type electrolytic capacitors.

An electrolytic paste made up of ammonium tetraborate and glycol is used in Dry type
electrolytic capacitors.
21. What is meant by electric susceptibility?
Electrical Susceptibility (
)
The polarization vector (P) is proportional to the applied electric field (E), for field strengths that
are not too large. So we can write
…(1)
is a characteristic of every dielectric and which is called electrical susceptibility.
Since
Therefore,
22. What is meant by ferro electricity? List out some ferro electric materials.
Ferro-Electricity
When a dielectric material exhibits electric polarization even in the absence of external field, it is
known as ferro-electricity and these materials are termed as ferro-electrics.
Examples:

Rochelle salt

potassium niobate

Lithium tantalate

Barium titanate

Lithium niobate etc
23. What arre the properties of ferro-electrics?

The dielectric constant of this ferro-electric material is above 2000 and it will not vary with
respect to temperature.

The dielectric constant reaches maximum value only at a particular temperature called Curie
temperature.

The polarization does not vary linearly with respect to electric field and hence these materials
are also called as non-linear dielectrics.

Ferro-electrics exhibits electric polarization very easily, even in the absence of external electric
field.
24. Write any four application of ferro-electrics.

Ferro-electric materials are used to produce ultrasonics

They are used in the production of piezo-electric materials and in turn to make microphones.

Ferro-electrics are also used in SONAR, strain gauges, etc.

Ferro-electric semiconductors are used to make positors, which in turn are used to measure and
control the temperature.
UNIT V
ADVANCED ENGINEERING MATERIALS
1. What are metallic glasses?
Metallic glasses are new type of materials which share the properties of both metals and
glasses. In general, they are strong, ductile, malleable, opaque and brittle. They also have good
magnetic properties and corrosion resistance. They are also called as amorphous metals.
Properties of metals + Properties of glasses = Properties of metallic glasses
2. What is the advantage of using metallic glasses as transformer core material?
Metallic glasses are ferromagnetic materials having low magnetic loss, high
permeability, saturation magnetization and low coercivity.
Advantages:
They have high hardness and almost zero magnetostriction. Transformers made of
metallic glass are small in size and more efficient.
3. Name any four applications of metallic glasses.

They are used in cores of high power transformers
Ex: Fe75 P15 C10, Fe24 Zr76

Metallic glasses are malleable and ductile and hence they are used in filament winding to
reinforce pressure vessels

They are used to make different kinds of springs as they are very strong in nature.

They have corrosion resistance and hence they can be used in surgical clips and marine
vessels
4. What are shape memory alloys?
Shape Memory Alloys (SMAs) are the alloy which changes its shape from its original
shape to new shape and while heating/cooling it will return to its original shape.
5. What are the merits and demerits of SMA?
Advantages

SMA is very compact in nature

It is safe and smart

They are flexible

They are non – corrosive
Disadvantages

Cost is high

Efficiency is low

Transformation occurs over a range of temperatures

Structural arrangements may sometime get deformed
6. What are nano phase materials?
Nanophase materials are materials with a grain size in the 1 to 100 nm range and these
atoms will not move away from each other.
7. Name any four methods employed to produce nano phase materials.

Plasma – arching

Chemical vapour deposition

Sol – gel technique

Electro – deposition
8. What is meant by Super elasticity?
Super elasticity
The shape memory alloys which have change in its shape at constant temperature are
called super elastic SMAs and that effect is known as super elasticity.
9. Define Nano technology
Nanophase materials exhibit greatly altered mechanical properties compared to their
normal, large-grained counterparts with the same chemical composition. For example,
nanophase metals are up to five times harder than the normal materials. While nanophase
metals generally become harder and more brittle, nanophase ceramics become more ductile. In
a typical nanophase material, 10 to 50% of the atoms are in grain boundary regions. These new
materials are called nano materials and the developed technology is called nano technology.
10. State any four properties of nano phase materials
(i) Physical Properties
a) Interparticle spacing is very less in nano materials
b) They have high strength and super hardness because it does not have any dislocation in
it.
c) The melting point of nano materials will be very less.
(ii) Electronic Properties
a) Energy bands in these materials will be very narrow.
b) The ionization potential is very high for nano materials.
c) They have more localized molecular bonds.
(iii) Magnetic Properties
a) The atoms will have less co-ordination number and hence possess local magnetic
moment within themselves.
b) They exhibit spontaneous magnetisation.
c) Ferro – magnetic and anti - ferro magnetic multi layer nano materials has GMR (Giant
Magneto Resistance) effect.
d) The nano materials shows variation in their magnetic property, when they change from
bulk state to cluster state.
(iv) Mechanical Properties
a) The hardness of nano phase materials varies from material to material. This may be due
to the phase transformation, stress relief, density and grain boundaries.
b) They exhibit super plastic behaviour.
11. What is meant by glass transition temperature?
Glass Transition Temperature
The temperature at which the metals in the molten form transforms into glasses (i.e. from
liquid to solid) is known as glass transition temperature.
12. What do you understand by the term Quenching?
Quenching means rapid cooling Atoms move freely in the liquid state. When the liquid
is quenched (rapidly cooled) it results in an irregular pattern, which results in the formation of
metallic glasses.
13. What are the types of Met glasses?
Metal - metal metallic glasses
They are formed by combination of metals.
Example:
(i) Ni - Nb (Nickel & Niobium)
(ii) Mg - Zn (Magnesium & zinc)
(iii) Cu - Zr (Copper & Zirconium)
(iv) Hf - V (Hafnium & Vanadium)
2. Metal - metalloid metallic glasses
They are formed by combination of metals and metalloids.
Example:
Metals like Fe, Co, Ni and metalloid such as B, Si, C, P
14. Mention any four properties of met glasses?
(i) Structural properties

They have tetrahedral closely packed structure rather than hexagonal closely
packed structure

They do not have any crystal defects
(ii) Mechanical properties

They are strong in nature

They have high corrosion resistance

They posses malleability and ductility
(iii) Magnetic properties

They can be easily magnetized and demagnetized

They have narrow hysteresis loop
(iv) Electrical properties

High electrical resistance

Electrical resistance will not vary with temperature

Low eddy current losses
15. List out any two recent applications of nano materials

Recently nano robots were designed, which are used to remove the damaged cancer
cells and also to modify the neuron network in human body.

Nano – dimensional photonic crystals and quantum electronic devices plays a vital
role in the recently developed computers.
16. What is transformation temperature?
In SMA, the transformation occurs not only at a single temperature rather they occur over a
range of temperatures.
Thus, the range of temperature at which the SMA switches from new shape to its original
shape is called transformation temperature or memory transfer temperature.
17. What do you understand by Martensite and Austenite Phases?
(i)Austenite
 Austenite is the solid solution of carbon and other alloying elements in γ - iron
 It crystallizes into cubic crystal structure
 It is a high temperature phase and it is hard in this phase
(ii) Martensite
 Martensite is an interstitial super solution of carbon in α – iron.
 It crystallizes into twinned structure
 It is a low temperature phase and it is soft in this phase
18. Define pseudo elasticity.
Pseudo elasticity
Pseudo elasticity occurs in some type of SMA in which the change in its shape will
occur even without change in its temperature.
19. What are the properties of SMA?

Transformation occurs not only at a single temperature rather they occur over a
range of temperatures.

Pseudo elasticity

Super elasticity

Hysteresis

Crystallographically thermo – elastic martensities are reversible.
20. What are the types of SMA?
TYPES OF SMA
(i) One – way SMA
The SMA remains in the same phase even though there is some change in its
temperature, and hence this type of material is called one way shape memory alloy.
(ii)Two – way SMA
The type of materials which produces spontaneous and reversible deformation just upon
heating and cooling even without load are called two way shape memory alloys.
21. Give any four application of SMA.

It is used in eye glass frames, Blood – clot filter

It is used in making toys

It is used in helicopter blades

It is used in fire safety valves

It is used in coffee makers
22. Define NLO optics.
Nonlinear optics is the study of the interaction of intense electromagnetic field with
materials to ace modified, which is different from the input field, both in amplitude and phase.
23. Define Birefringence
When light passes through a material the incident ray splits into two rays viz, one of
same wavelength and other of different wavelength. This phenomenon is called as double
refraction (or) Birefringence.
24. What are NLO materials? List out NLO materials.
The change in optical properties due to electric and magnetic field associated with light
is called non linear effects and those materials which posses these effect are called non-linear
materials.
Examples:
i.
Ammonium-dihydrophosphate (APO)
ii.
Potassium-dyhydrophosphate (KDP)
25. What is fararday effect?
Faraday Effect
When magnetic field applied along the axis of propagation of light beam to a glass
medium, the plane of polarisation of light is rotated. This is called Faraday Effect.
26. Define Kerr effect.
Kerr effect
When electric field is applied along the direction of propagation of light, then the light
will undergo double refraction, this is called Kerr Effect.
27. Write some properties of NLO materials.

It is a synthetic ferroelectric materials.

It has highest curie temperature.

At high temperature it becomes electrically conductive.

It has multi domain structures.

Polarization is inversely proportional to the temperature.