M.Sc. Physic (Materials Science (Sem.III) (CBCS) Examination
2017
DIELECTRIC AND FERROELECTRIC PROPERTIES OF MATERIALS
Day Date: Tuesday, 25-04-2017 Max. Marks: 70
Time: 02.30 PM to 05.00 PM
Instructions: Question No. 1 and 2 are compulsory
Attempt any 3 questions from Q.No.3 to Q.No.7
Figures to the right indicates full marks.
Q.1 Objective Questions 14
Select correct alternatives. 06
Net outflow of flux through a closed surface enclosing a
charge q is
q 1/q 0 q/4
The flux density is related to the electric field as
E
The orientation polarizability per molecule in a polyatomic gas
is proportional to
T T2 1/T 1/T2
Piezoelectric effect is production of electricity by
Chemical effect Varying effect
Temperature Pressure
In a dielectric, the polarization is
Linear function of applied field
Square function of applied field
Zero polarization
Positive polarization
The factors responsible for spontaneous polarization is
Free electron Atoms
Permanent dipoles None of these
Fill in the blanks 04
The polarization P is defined as
Electric susceptibility is related to dielectric constant by
The relation between CGS, where is
polarizability.
Page 2 of 2
BaTiO3 undergo transition around 120 0C.
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.
A ferroelectric crystal exhibits an electric dipole moment even
in the absence of an external electric field.
In case of NTC materials resistance increases with increase in
temperature.
ABO3 type pervoskite structure consists of five atoms per unit
cell in barium titanate.
Q.2 Write short notes 14
Maxwell's equation, Electric polarization and relaxation 5
Cole Cole plot, Magneto Optic effect 5
PTC and NTC materials. 4
Q.3 What is polarization? Sketch the line of force of a dipole?
Explain what depolarization field is. Sketch the picture of
depolarization field and polarization in presence of applied
electric field.
08
State and prove Gauss theorem in electrostatics. 06
Q.4 Obtain Clausius Mosotti relation and explain how it can be
used to determine the dipole moment of a polar molecule from
the dielectric constant measurements.
08
What do you mean by complex dielectric constant? 06
Q.5 Distinguish between polar and non polar substances. Describe
behavior of polar substance in an alternating field.
08
Explain phenomenon of spontaneous polarization in ferroelectric
materials.
06
Q.6 Discuss the relation between structural phase transition and
ferroelectric phase transition observed in case of BaTiO3.
08
Explain Ferroelectricity and Antiferroelectricity in dielectrics. 06
Q.7 What is pyroelectric effect? Explain Pyroelectric parametes and
their measurements.
08
What are the applications of piezoelectric materials? 06