M.Sc. (Semester III) (CBCS) Examination Mar/Apr-2018
Physics (Materials Science)
DIELECTRIC FERROELECTRIC PROPERTIES OF MATERIALS
Time: 2½ Hours
Max. Marks: 70
Instructions: Q.1 and Q.2 are compulsory. Attempt any 3 questions from Q. 3 to 7. All questions carry equal marks. Use of non-programmable calculator is allowed.
Q.1

Select Correct alternatives:
08
What symmetry element must be absent for a material to be ferroelectric?
An axis of rotation
A mirror plane
A centre of symmetry
An improper axis of rotation
Which of these is not a correct definition of polarization?
The net dipole moment per unit volume
The surface charge per unit area
The movement of atoms giving rise to a dipole moment
The net charge per dipole moment
The polarization of a sold which contain N number of particles per unit volume is equal to




The internal or Lorentz field is equal to




For a given dielectric, as the temperature increases, the ionic polarizability
Increases
Decreases
Remains unaltered
None of these
The unit of dipole moment per unit volume is



Coulomb
Applying a mechanical stress to a piezoelectric does not cause which of these?
The formation of a dipole moment
The movement of atoms
Development of polarization
The generation of an internal current
In a ferroelectric material, as the applied field is gradually reduced to zero, the polarization still left is known as
Remanent polarization
Coercive polarization
Zero polarization
Positive polarization
Page 2 of 2
SLR-UN-486

State whether the following statement is True or False:
06
For a single-point charge with total net charge in free space, can be written as,
The amount of rotation in angle is proportional to the magnetic filed H and is given by
Helmholtz free-energy function which is given by
Crystals formed by polar molecules with a centrosymmetric structure will exhibit a piezoelectric effect
Pyroelectricity occurs only when the material exhibits spontaneous polarization.

Q.2
Write a short note on:
14
Polar and nonpolar dielectrics
04
Cole-Cole plot
05
Magneto-Optic effect
05
Q.3
Give an account for Kramers Kronig Relations.
08
Write short note on Acousto-Optic effect.
06
Q.4
Discuss in detail the vibrational atomic/ ionic polarization mechanism.
08
Write short note PTC materials.
06
Q.5
Give an account for Time-Dependent Electric Polarization.
08
Write short note on conducting materials.
06
Q.6
Give an account for phenomenological approach to piezoelectric effects.
08
Write short note on BaTiO3 and its unit cell
06
Q.7
Give an account for spontaneous, space charge and hopping polarization.
08
Write short note on dielectric relaxation phenomena.
06