Third Entity in Universe: Information

The discovery of information in the origin of both the universe and life itself is what makes this concept so important in the modern world. Scientists today are realizing that the universe is formed by "matter, energy and information," and this is replacing the materialistic philosophy of the nineteenth century that defined the universe as being made up entirely of "matter and energy."

So, what does this all mean?

Let's explain through an example, that of DNA. All living cells function according to the [color]genetic information in the double helix structure of DNA. Our bodies are also formed by trillions of cells each with its own DNA, and all the functions of our bodies are registered in this giant molecule. Our cells use protein codes inscribed in the DNA to produce new proteins. The information that our DNA possesses is so large that if you wanted to write it down, it would fill up 900 volumes of encyclopedias, cover-to-cover!

So what is DNA made up of? Fifty years ago, scientists would have replied that DNA is formed by nucleic acids called nucleotides and the chemical bonds holding these nucleotides together. In other words, they used to list only the material elements of the DNA. But today, scientists have a different answer: DNA is composed of atoms, molecules, chemical bonds and, most importantly, information..

It's just like a book. We would be quite mistaken to say that a book is only made up of paper, ink and binding for, alongside these materials, it is the information that truly makes it a book. It is information which separates a volume of the Encyclopedia Britannica from a "book" formed by randomly arranged letters like ABICLDIXXGGSDLL. Both have paper, ink and binding, but one has information while the other does not. The source of information is the author of that book, a mind with consciousness. Therefore we can't deny that the information in DNA was placed there by an intelligent being.

HCP

FACE CENTRED CUBIC (fcc)

Body centred cubic (bcc)

ATOMIC PACKING FACTOR: BCC

APF for a body-centered cubic structure = p3/8 = 0.68

Atomic Packing Fraction

SIMPLE CUBIC





APF for a simple cubic structure = 0.52

Miller Indices

Miller Indices :

1. Find the intercepts made by plane on the Crystallographic axes
2. Express intercepts in terms of axial units of unit cell dimensions
3. Take the reciprocals of the intercepts
4. Reduce them to smallest integer by multiplying with their LCM and write them in parantheses.

Important features of Miller Indices:

1. For any plane parallel to any axis, the intercept is made at infinity and corresponding Miller index is zero.
2. All parallel equidistant planes have same Miller indices.
3. If a plane passes through origin then the Miller indices are found by taking a parallel plane having non zero intercepts.
4. If a plane cuts the negative axis then a bar is put on the Miller index.
5. If a normal is drawn to a plane, then it represents the direction of the plane [hkl]

hi folks.. happy independence day

Assignment-I

1.What are basic lattice parameters?
2.Define space lattice
3.Define unit cell
4.Name the seven crystal systems.
5.Define primitive cell
6.What are Bravais lattices?
7.What is meant by nearest neighbour distance?
8.Define atomic radius
9.Define coordination number
10.Define effective number
11.Define atomic packing factor
12.What are Miller indices?
13.Draw the crystal planes with Miller indices (100) (110)
14.What is the relation between innerplanar spacing and inter atomic distance?
15.Draw the plane of a cubic unit cell with Miller indices (210)

Crystal Systems & Bravais Lattices

Unit Cell

Unit Cell:

The smallest part of a crystal is called as unit cell. It is formed by combination of atoms and molecules. The whole crystal structure can be formed by the repetition of these unit cells.

Crystal Physics

Crystal Structure :

In Crystal there is systematic , periodic arrangement of atoms in all the three directions . Crystal has regular shape and sharp melting point. Crystals possess directional properties and hence called as anisotropic substances.

Examples of crystals : Copper, silver, aluminium, tungsten and magnesium.


Space Lattice :

An infinite array of points repeated in 3 dimensional space such that every point has surroundings identical to every other point in the array is called Space lattice.

Physics I (Ph101) syllabus

UNIT 1 CRYSTAL PHYSICS 9
Introduction – Space lattice – unit cell – Bravais lattices – Miller Indices for cubic crystals – Inter planar spacing in cubic lattice – simple crystal structures – SC, BCC, FCC and HCP structures – atomic radius, coordination number, Packing factor calculation – crystal imperfections – point, line and surface defects – Burger vector.

UNIT II QUANTUM PHYSICS 9
Black body radiation – Planck’s theory of radiation – deduction of Wien’s displacement law and Rayleigh – Jeans law from Planck’s theory – Compton effect – Theory and experimental verification – Dual nature of matter – De Broglie’s wavelength- physical significance of wave function – Schroedinger wave equation – time independent and time dependent wave equation – particle in one dimensional box.

UNIT III WAVE OPTICS 9
Polarization – double refraction – Theory of plane polarized,circularly polarized and elliptically polarized light – Quarter wave plate, Half wave plate – production and detection of plane, circularly and elliptically polarized lights – photoelasticity – photo elastic effect – stress optic law – effect of stressed model in a plane polariscope – isoclinics and isochromatic fringes –photo elastic bench.

UNIT IV ULTROSONICS AND NDT 9
Ultrasonics – production – magnetostriction and piezo electric methods – properties of ultrasonic waves – Detection of ultrasonic waves – Applications – Acoustical grating – SONAR – depth of sea – measurement of velocity of blood flow – Non Destructive Testing (NDT) methods – Liquid penetrant method – ultrasonic flaw detector – A,B and C scan displays – X – ray radiography and fluoroscopy.
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UNIT V LASER AND FIBRE OPTICS 9
Characteristics of laser light – Einstein’s A & B coefficients (derivation) – Nd:YAG laser – He -Ne laser – CO2 laser – homo and hetero junction semiconductor lasers – applications – material processing and holography (construction and reconstruction of hologram) – Optical fibre – principle of propagation of light in optical fibers – Numerical aperture and acceptance angle – single and multimode fibres – step index and graded index fibres – applications – fibre optic communication system (block diagram only)- fibre optic sensors (displacement and pressure sensors (qualitative).

TEXT BOOKS:
1. Avadhanulu M.N., Engineering Physics, 1st Edition, S.Chand & Company Ltd., New Delhi, 2007.
2. Gaur R.K. and Gupta S.L., Engineering Physics, 8th edition, Dhanpat Rai Publications (P) Ltd., New Delhi, 2003.

REFERENCES:
1. Uma Mukherji, Engineering Physics, Narosa Publishing House, New Delhi, 2007.