Unit I - Properties of Matter
Elasticity: Elastic and plastic materials – Hooke’s law – elastic
behavior of a material – stress - strain diagram – factors affecting
elasticity. Three moduli of elasticity – Poisson’s ratio – torsional
pendulum – twisting couple on a cylinder. Young's modulus uniform bending – non-uniform bending. Viscosity: coefficient of
viscosity – streamline and turbulent flow - experimental
determination of viscosity of a liquid – Poiseuille’s method.
Unit II - Applied Optics
Interference: Air wedge – theory – uses – testing of flat surfaces –
thickness of a thin wire. Laser: Introduction – principle of laser characteristics of lasers - types of lasers - CO2 laser –
semiconductor laser (homo junction). Fiber optics: Principle of
light transmission through fiber - expression for acceptance angle
and numerical aperture - types of optical fibers (refractive index
profile and mode) - fiber optic communication system (block
diagram only).
Unit III - Ultrasonics
Ultrasonics: Introduction – properties of ultrasonic waves –
generation of ultrasonic waves: Magnetostriction - piezo electric
methods – detection of ultrasonic waves. Determination of
velocity of ultrasonic waves (acoustic grating). Applications of
ultrasonic waves: SONAR – measurement of velocity of blood
flow – study of movement of internal organs.
Unit IV - Solid State Physics
Crystal Physics: Lattice – unit cell – crystal systems - Bravais
lattices – Miller indices – ‘d’ spacing in cubic lattice – calculation
of number of atoms per unit cell, atomic radius, coordination
number and packing density for SC, BCC, FCC and HCP
structures - X-ray diffraction: Laue’s method – powder crystal
method.
Unit V - Quantum Mechanics
Quantum Physics: Development of quantum theory – de Broglie
wavelength – Schrödinger’s wave equation – time dependent and
time independent wave equations – physical significance.
Application: Particle in a box (1d) – degenerate and nondegenerate states. Photoelectric effect: Quantum theory of light
work function – problems.
Unit VI*
Neutrinos - neutrino observatory - European center for nuclear
research. Expanding universe – dark matter in galaxies.
*Self Study/ Seminar Presentation
Photo © Vol. 10
PhotoDisk/Getty
BUNGEE jumping
utilizes a long elastic
strap which stretches
until it reaches a
maximum length that
is proportional to the
weight of the jumper.
The elasticity of the
strap determines the
amplitude of the
resulting vibrations. If
the elastic limit for
the strap is
exceeded, the rope
will break.
Elastic Properties of Matter
An
An elastic
elasticbody
body isis one
one that
that returns
returns to
to its
its original
original
shape
shape after
after aa deformation.
deformation.
Slinky Toy
Rubber
Band
Soccer Ball
Elastic Properties of Matter
An
An inelastic
inelasticbody
body isis one
onethat
thatdoes
does not
not return
return to
to its
its
original
originalshape
shape after
after aa deformation.
deformation.
Dough or Bread
Clay
Inelastic Ball
An Elastic Spring
A spring is an example of an elastic body that
can be deformed by stretching.
x
F
AArestoring
restoringforce,
force,F,
F, acts
acts
in
in the
the direction
direction opposite
opposite
the
of the
the
the displacement
displacement of
oscillating
oscillating body.
body.
FF == -kx
-kx
Hooke’s Law
When a spring is stretched, there is a restoring
force that is proportional to the displacement.
FF =
= -kx
-kx
x
m
The spring constant
F k is a property of
the spring given by:
F
k
x
The
The spring
spring constant
constant kk isis aa measure
measure
of
of the
the elasticity
elasticity of
of the
the spring.
spring.
Stress and Strain
Stress refers to the cause of a deformation, and
strain refers to the effect of the deformation.
The downward force F
causes the displacement x.
x
F
Thus, the stress is the force;
the strain is the elongation.
To understand the elastic and plastic
behaviour of materials using Hooke’s
law
Objectives: After completion of this
module, you should be able to:
1. Classify two types of materials based on
deformation behaviour (S)
2. Differentiate elasticity and plasticity (S)
3. State Hooke’s law (S)
4. List the three types of stress and derive its
units (S, M)
5. Identify the three types of strain (S)
Definitions
Stress is the ratio of an applied force F to the
area A over which it acts:
Stress 
F
A
N
Units : Pa  2
m
Strain is the relative change in the dimensions or
shape of a body as the result of an applied stress:
Examples:
Examples: Change
Changein
in length
lengthper
per unit
unitlength;
length;
change
change in
in volume
volume per
per unit
unit volume.
volume.
Types of Stress
1. Linear Stress
2. Bulk Stress
3. Shearing Stress
x
F
Example 1. A steel wire 10 m long and
2 mm in diameter is attached to the
ceiling and a 200-N weight is attached
to the end. What is the applied stress?
L
L
A
A
F
First find area of wire:
 D 2  (0.002 m) 2
A

4
4
A = 3.14 x 10-6 m2
F
200 N
Stress  
A 3.14 x 10-6 m 2
Stress
6.37 x 107 Pa
Example 1 (Cont.) A 10 m steel wire
stretches 3.08 mm due to the 200 N
load. What is the longitudinal strain?
Given: L = 10 m; L = 3.08 mm
L
L
L 0.00308 m

Srain 
10 m
L
Longitudinal Strain
3.08 x 10-4
The Elastic Limit
The elastic limit is the maximum stress a body can
experience without becoming permanently deformed.
2m
2m
F
Okay
F
Stress 
A
W
W
W
Beyond limit
If the stress exceeds the elastic limit, the final
length will be longer than the original 2 m.
Example 2. The elastic limit for steel is
2.48 x 108 Pa. What is the maximum
weight that can be supported without
exceeding the elastic limit?
Recall: A = 3.14 x 10-6 m2
L
L
A
A
F
F
Stress   2.48 x 108 Pa
A
F = (2.48 x 108 Pa) A
F = (2.48 x 108 Pa)(3.14 x 10-6 m2)
FF == 779
779 N
N
Hooke’s Law
Provided that the elastic limit is not exceeded,
an elastic deformation (strain) is directly
proportional to the magnitude of the applied
force per unit area (stress).
stress
Modulus of Elasticity 
strain
Example 3. In our previous example,
the stress applied to the steel wire was
6.37 x 107 Pa and the strain was 3.08 x 10-4.
Find the modulus of elasticity for steel.
L
L
Stress 6.37 x 107 Pa
Modulus 

Strain
3.08 x 10-4
99Pa
Modulus
=
207
x
10
Modulus = 207 x 10 Pa
This
This longitudinal
longitudinal modulus
modulusof
of elasticity
elasticity isiscalled
called
Young’s
Young’s Modulus
Modulus and
and isis denoted
denoted by
by the
the symbol
symbol Y.
Y.
Three types of strain



Linear strain
Shear strain
Volumetric strain
Three types of stress



ELASTICITY
Linear stress
Shear stress
Volumetric stress
&
PLASTICITY
Two types of materials

Elastic

Plastic


Applications
Engineering–Beams,
gliders
Medical field – gloves,
surgical tools
Hooke’s law
Stress α strain
Examples of elastic
materials
Rubber band
Spring
Metals and alloys
Examples of plastic
materials

Nylon

Styrofoam

Polythene

Teflon

PVC
Summary: Elastic and Inelastic
1. Two types of materials based on their
physical property
2. Difference between elasticity and plasticity
3. Examples of elastic and plastic materials
4. Hooke’s law
5. Three types of stress
6. Three types of strain
7. Three applications of elasticity
Stimulating questions
1. In general, no material is perfectly elastic or
perfectly plastic. Why?
2. Which is more elastic Steel or rubber. Justify
Thank you……