Master of Science II (Physics-Materials Science)
Examination: Oct Nov 2016 Semester IV (Old CGPA)
SLR No. Day
Date Time Subject Name Paper No. Seat No.
SLR SH
566
Tuesday
22/11/2016
02.30 PM
to
05.00 PM
Magnetic Materials
C
XI
Instructions: Q. no. 1 and Q. no 2 are compulsory
Attempt any three questions from Q. No.3 to Q. No. 7
All questions carry equal marks.
Total Marks: 70
Q.1 select correct alternative 08
Permanent magnets are made of
Soft magnetic materials Hard magnetic materials
Semi conductors Super conductors
Materials, which provide a path to the magnetic flux, are classified as
Insulting materials Semi conducting materials
Magnetic materials Dielectric materials
Ferrites are
Ferromagnetic materials Ferrimagnetic materials
Anti ferromagnetic material Diamagnetic materials
The relative permeability of a paramagnetic substance is
Unity Slightly more than unity
Zero Less than unity
Hall effect is associated with
Insulators Solders
Thermistors Semiconductor
Magnetic materials
Provide a path to magnetic flux Are good insulators
Are semiconductors None
Magnetic field strength's units are
Wb/m2 Wb/A.m
A/m Tesla/m
Example of antiferromagnetic materials is
Salts of transition elements Rare earth elements
Transition metals Ferrites
Page 1 of 2
State True of False 06
Magnets have a north seeking pole and a south seeking pole.
Two opposite poles attract each other.
When magnets are broken into small bits, the bits themselves can become
small magnets
The thickness of Bloch walls is 100nm
Ferrites are example for ferro-magnetic materials.
The ability of a material to maintain a magnetized state (without the presence
of a magnetizing force) is called hysteresis.
Q.2 Write short notes
Altering (field) gradient magnetometer.
Magnetic resonance.
Exchange forces.
05
05
04
Q.3 Explain the quantum theory of para magnetism.
Discuss the ferromagnetism phenomenon.
08
06
Q.4 Explain the molecular field theory above TN and below TN
What is diffraction? Explain the neutron diffraction
10
04
Q.5 What are ferrites? Explain structure of cubic and hexagonal ferrites
What is anisotropy? Explain it in cubic and hexagonal Crystals.
08
06
Q.6 Explain the magnetic anisotropy measurement from magnetization curves.
What is magnetostriction? Explain it in cubic crystals and polycrystals.
08
06
Q.7 What is the domain wall motion? Explain magnetization in low and high
fields.
Explain the shapes hysteresis loop of a magnetic material.
10
04