M.Sc. (Semester IV) (CGPA) Examination Oct/Nov-2017
Materials Science
MAGNETIC MATERIALS
Day Date: Wednesday, 22-11-2017 Max. Marks: 70
Time: 02.30 PM to 05.00 PM
Instructions: Q. and Q. are compulsory.
Answer any three questions from Q.3 to Q.7.
All questions carry equal marks.
Use of non-programmable calculator is allowed.
Q.1 Objective questions: 08
Magnetic Susceptibility for a
Metal Semiconductor
Insulator Superconductor
Above the Neel Temperature
The diamagnetism vanishes
The paramagnetism vanishes
The ferrimagnetism vanishes
The antiferromagnetism vanishes
In nickel-zinc ferrite with Zn/Ni atom ratio equal to the number of
unpaired electron spins present per



2−is (assume
that zinc ions push the ferric ions from tetrahedral sites to octahedral
sites and changes their spins).
5 3.75
1.25 4.5
Exchange interaction between any two electrons is


The typical value of domain is
10-2 m3 10-6 m3
10-10 m3 10+6 m3
The phenomenon in which a change in the shape of certain
ferromagnetic material is produced when they are subjected a
magnetic field, in known as
Electrostriction Magnetostriction
Piezoelectric effect Anisotropic effect
The SrFe12O19 is
Hexaferrite Spinel ferrite
Dielectric Superconductor
Curie law is valid for
Diamagnet Paramagnet
Ferromagnet All substances
Page 2 of 2
SLR-MO-537
State True or False/ Fill in the blanks: 06
The magnetic spin arrangements are explained using Exchange
interaction energy.
The dipoles are aligned antiparallel with unequal magnitude in
antiferromagnetic materials.
Fe3O4 is a magnetostrictive material.
The magnetic dipole moment is the product of current in the loop and
square of area enclosed by the current loop
Magnetic induction B and magnetic field intensity H are related by B
μmH.
The typical value of the thickness of the Bloch wall is 10 cm.
Q.2 Write short notes: 14
Hall effect 04
Magnetic anisotropy measurement from magnetization curve 05
Exchange forces 05
Q.3 Explain in detail the classical theory of paramagnetism. 08
Explain the magnetic properties of garnets with suitable example. 06
Q.4 Discuss the magnetic characteristics of diamagnetic, paramagnetic,
ferromagnetic, and antiferromagnetic and ferrimagnetic materials on
account of their magnetic moments as well as magnetic susceptibilities.
08
Discuss the domain wall structure. 06
Q.5 Discuss the anisotropy in hexagonal crystals and explain the physical
origin of crystal anisotropy.
08
Discuss any method used for the determination of magnetic susceptibility. 06
Q.6 Define magnetostriction and discuss the physical origin of
magnetostriction.
08
Write short note on torque magnetometer. 06
Q.7 Explain the molecular field theory above and below TN in
antiferromagetism.
08
Write a short note on vibrating sample magnetometer. 06