M.Sc.(Semester III) (CBCS) Examination Oct/Nov-2017
Physics (Materials Science)
DIELECTRIC FERROELECTRIC PROPERTIES OF MATERIALS
Day Date: Tuesday, 21-11-2017 Max. Marks: 70
Time: 02:30 PM to 05.00 PM
Instructions: Q. No. and Q. No are compulsory.
Attempt any three from Q. No. To Q. No.
All questions carry equal marks.
Q.1

Objectives Questions:-
Select correct alternative:
14
06
When mono-atomic gas is placed in a uniform electric field the
displacement of the nucleus is proportional to
E2 E
E3 Independent of E
For a given dielectrics, as temperature increases, the ionic polarizability

Increases
Decreases
Remains unaltered
Keeps on increasing exponentially
Above Curie temperature, the hysteresis loop of ferroelectric material
merges into
Parabole Straight line
Point Ellipse
Effects is production of electricity by a pressure.
Chemical Varying
Pyrroelectric Piezoelectric
The factor responsible for spontaneous polarization is
Free electron Atoms
Permanent dipoles None of these
In a dielectric, the polarization is
Linear function of applied field
Square function of applied field
Zero polarization
Positive polarization
Fill in the blanks:- 04
BaTiO3 undergo Ferroelectric phase transition around
Piezoelectric strain constant is
When polarization is uniform within the body the contribution to the
macroscopic field are from
Three important types of polarization in dielectrics under the action of
external electric fields are ii) iii)

State True or False:- 04
Gauss theorem tells that total normal electric induction through a
closed surface is equal to charge enclosed by the surface.
In NTC materials resistance increases with increase in temperature.
Spontaneous polarization in case of ABO3 type ferroelectric becomes
zero at ferroelectric-paraelectric transition temperature.
Materials with large electronic and ionic polarizabilities are used for
making dielectric capacitors.
Q.2 Write short notes on: 14
Electric polarization and relaxation. 05
Photorefractive effect 05
PTC and NTC materials. 04
Q.3 Deduce a relation of Clausius Mosotti and explain how it can be used to
determine the dipole moment of a polar molecule from the dielectric
constant measurement.
08
Explain in brief complex dielectric constant. 06
Q.4 What is polarization? Sketch the line of force of a dipole? Explain what
depolarization field is. Sketch the picture of depolarization filed and
polarization in presence of applied electric filed.
08
State and prove theorem in electrostatics. 06
Q.5 Discriminate between polar and non polar materials. Explain behavior of
polar materials in an alternating field.
08
Spontaneous Polarization in ferroelectric materials: Explain. 06
Q.6 Structural phase transition and Ferroelectric phase transition observed in
case of BaTiO3: Explain
08
What do you mean by Ferroelectricity and Antiferroelectricity in dielectrics. 06
Q.7 What is pyroelectric effect? Explain pyroelectric parameters and their
measurements.
08
Explain applications of Piezoelectric materials. 06