Problems with Bangladesh Railway
From the beginning of the Bangladesh Railway it developed a lot but still it has many problems
and that is the reason why Bangladesh Railway is lagging behind than oth
GROUP VELOCITY
Group of waves with possibly different phase velocities:
Pure sinusoidal wave: Y(x,t) = A cos(kx-t+o) = A cos()
where = (x,t) = phase angle = kx-t+o
where k = 2 radians/ (kx is then an
Temperature dependence on the diffracted x-rays
1. Initial expectation: since heat adds energy to the crystal, the
atoms will probably vibrate causing the lattice constant, a, to
oscillate somewhat ra
Introduction to Part 2
1.
We now have lattice structure as confirmed by Bragg diffraction.
a) As temperature goes up, Bragg diffraction lines do NOT broaden
as would happen in a gas, but we do get mor
Bragg Diffraction:
A rough and simple look
1. Assumption: Instead of discrete atoms, we will consider the lattice
to be made up of continuous planes where each atom (more specifically,
the basis) is l
FOURIER SERIES:
1.
an example - the SAWTOOTH WAVE
Define the repeating function:
F(x)
F(x) = Ax
for < x <
2.
x
The general form for the Fourier series:
f() = ao +
am = (1/)
3.
o
n=1
an cos(n) +
o
Crystal Structure
1. Atoms are bound together in a solid. Due to the nature of the forces that bind the
atoms together (and hence due to the energies involved), the atoms sometimes show a
high degree
BRAGG DIFFRACTION:
a more fundamental look
(Here vectors will be displayed in bold blue, unit vectors in bold
violet, and scalars (and components) in regular black.)
1.
Basic Idea: x-rays scatter off
Diffraction continued
1.
Brilluoin zone
a) Definition: The first Brilluoin zone is the Wigner-Seitz cell
in the reciprocal lattice.
b)
Review:
b1) The Wigner-Seitz cell is a cell that is bounded by
pe
PHYS 252
Elementary Particles Supplement
4
page
ELEMENTARY PARTICLES
I.
INTRODUCTION:
Nucleons are held together inside the nucleus by something other
than the gravitational or electrical force. Hence
Nuclear Physics
size of atoms:
take water (H2O)
density = 1 gm/cc,
atomic weight = 18 gm/mole, (alternately, get
mass of one molecule from mass spectrograph)
Avagadros number = 6 x 1023/mole
(1 cm3/gm
Speed of Light
How fast is the speed of light?
depends on material:
in vacuum, c = 3 x 108m/s
What is this speed relative to?
What is the speed of sound relative to?
the ground? the air? the sou
NUCLEAR DATA SHEET
I.
UNITS OF RADIOACTIVITY:
Activity: Curie (Ci) = 3.7 x 1010 dis/sec (activity of 1 gm of Ra226 )
MKS: Becquerel (Bq) = 1 dis/sec = 27 pCi
Exposure: Roentgen (R) = (1/3) x 10-9 Coul
Refraction
Snells Law: n1 sin( 1) = n2 sin( 2)
where n1 = c/v1 and v1 = [1/ ]1/2
and = K o where K = K( ) .
This means that n = n( ), and this means
that -transmitted depends on the
frequency.
Thus di
Waves (in general)
sine waves are nice
other types of waves (such as square waves,
sawtooth waves, etc.) can be formed by a
superposition of sine waves - this is called
Fourier Series .
This means t
Making Light
How do we make light?
Making Light
How do we make light?
Heat and Light: Incandescent Lighting
(3-5% efficient)
Atoms and Light: Fluorescent Lighting
(20-40% efficient)
Well consider
Photoelectric Effect
Light hits a metal plate, and electrons are
ejected. These electrons are collected in the
circuit and form a light
current.
ejected electron
A
-+
V
Photoelectric Effect
The follow
PHYS 252
Part 1: Light
what is light?
Light
what is light:
wave or particle?
moving energy
Light
what is light:
wave or particle?
how do we decide?
moving energy
Light
what is it?
moving energy
w
Diffraction: single slit
How can we explain the pattern from light
going through a single slit?
screen
w
x
L
Diffraction: single slit
If we break up the single slit into a top half
and a bottom half,
PHYS 353 SYLLABUS
Independent Study
CATALOG DESCRIPTION: PHYS 353 Solid State Physics
A study of solids including crystal structure and binding, lattice vibrations (phonons) and
thermal properties, th
PHYS 353 SOLID STATE PHYSICS STUDY GUIDE FOR PART 4
Semiconductors and Superconductors
Chapters: 8,12
OUTLLINE:
A. Band gap:
1. origin of band gap;
2. value of Eg for various materials;
B. Equations o
PHYS 353 SOLID STATE PHYSICS STUDY GUIDE FOR PART 2
Lattice Vibrations and Phonons
Chapters: 4,5
OUTLINE:
A. Vibrations of crystals
1. monatomic basis
2. two atoms per primitive basis
3. phonons
a) en
PHYS 252
STUDY GUIDE FOR PART II:
LIGHT II
Interference of Light Waves
1. Superposition of waves (Fourier series)
2. Young's double slit
n = d sin( n)
3. Diffraction grating
[same as above only sharpe
PHYS 252
Study Guide for Part 1
page
STUDY GUIDE FOR PART I: LIGHT I
PHYS 252
The Nature of Light and the Laws of Geometric Optics
A. What is Light?
1. a form of energy
2. wave or particle?
B. Waves (
PHYS 252
STUDY GUIDE FOR PART III: QUANTUM THEORY
INTRODUCTION:
Classical theory accounts for the results of many, many experiments and almost all of the everyday
experiences. But there are several ex
PHYS 252
STUDY GUIDE FOR PART IV: SPECIAL RELATIVITY
Special Theory of Relativity
A. The speed of light & the Michelson-Morley experiment
1. inertial frames
2. speed relative to what?
3. Michelson-Mor
PHYS 252 SYLLABUS
Spring, 2008
CATALOG DESCRIPTION: PHYS 252 Physics III
A third course in physics covering geometrical optics, interference, diffraction, quantum theory,
waves and particles, atomic p
PHYS 252
STUDY GUIDE FOR PART V
RADIOACTIVITY
Nuclear Physics
A. Nuclear Structure
Q-1; S-78
1. size of nucleus
2. structure of nucleus
3. the nucleus
a) charge - elements (Z number of protons in nucl