| February 28th marks a grand click start of year long celebrations in India of 1905 – the magnificent year in which Einstein published three of his major works. 2005 has been designated as International year of Physics by United Nations. The grand toast has already been raised by international scientific community particularly physicists to honour a great personality of our times – Dr. Albert Einstein (born Ulm - Germany March 14, 1879 to April 18, 1955). Except Issac Newton, no other physicist changed our version and vision of Universe and its understanding as Dr. Einstein did. Much credit is given to his inventions and postulations because they came at a time when two world wars were fought and much of the socio-economic and scientific developments were blurred by exponsionist political dogmas. An average student at Zurich (Switzerland) who even failed to get admission to graduate school, Einstein was packed off to Federal Patent Office in Born (Switzerland) to serve as a patent clerk. Far removed from extraordinary gadgets and facilities of laboratory and library, Albert worked ferociously for long hours to publish five papers in one year each of which is a gem by itself. He was all of just 26 years in 1905 when he achieved this unsurpassed feat. The year 1905 has just one comparable year of science before 1665 to 1666. This is the time when in span of 18 months Sir Issac Newton invented calculus, constructed a theory of optics, explained how gravity works and discovered his laws of motion. It was such a sustained sprint of intellectual achievement that, at that time no one thought it could be equaled. Newton, hence stood as the tallest physicist. Einstein too gave the world new forms of mathematics to support his arguments in physics. He showed that atoms (the smallest divisible particles of matter) are real (it was a controversy at that time). His first paper which fetched him a Nobel Prize in 1921 proved existence of photons particles in light. In 1922 he had received a paper from unknown Indian physicist (then) Satyendra Nath Bose who worked on behaviour of these light particles – photons. In laboratory situation, Bose – Einstein condensate was proved to be correct only in 1995 nearly forty years after death of Einstein. His paper triggered a flurry of research by a whole generation of young physicists which has codified the universe now. Quantum mechanics took firm shape in 1920s and 1930s after that paper from him. As such, Albert Einstein was not considered to be an adroit mathematician. His power lay in that he could visualize physical consequences of experimental results. In the same year 1905, Einstein realized that nothing can travel faster than light. His first relativity paper later lead to general theory of relativity. The consequence of his observation E=mc2 where ‘E’ represents energy, ‘m’ is the mass of a body and ‘c’ denotes speed of light – lead to creation of a bomb which caused the holocaust in Hiroshima and Nagasaki in 1945. One particular paper which served as doctoral thesis (Princeton, N.J.,U.S.) was beautiful but brief. It explained how sugar dissolves in water! He explained motion was caused by molecules hitting the particles. Till then the question of “Brownian motion” remained unexplained as how suspended particle in a solution behaved. Einstein’s theory proved that molecules are real and they exist!! Einstein wrote profound things in simplistic terms. He himself admitted this in 1932, “the real goal of my research has always been simplification and unification of the system of theoretical physics”. He once remarked about Newton calling him lucky ——“there is only one Universe to discover and he did it”, Of course, Albert was referring to laws of gravity of Issac Newton. There are many legends about intellectual capabilities of Einstein. He is even held to be a demigod of physics. Between 1905 and 1925 – Einstein transformed human understanding of nature on every scale. From smallest particles (atom) to the biggest (cosmos as a whole). The problems that he left behind uncracked, continue to form cutting edge technology studies. When the scientific community around the world is relocating itself to use all their knowledge of, geology, remote sensing, space science, weather forecast to understand Tsunami, memories of a saint scientist, Dr. Albert Einstein stands tall in our memory. (PIB Features) |
Showing posts with label Physics. Show all posts
Showing posts with label Physics. Show all posts
Saturday, November 21, 2009
Einstein
Saturday, November 14, 2009
Hooke's law
In mechanics, and physics, Hooke's law of elasticity is an approximation that states that the extension of a spring is in direct proportion with the load added to it as long as this load does not exceed the elastic limit. Materials for which Hooke's law is a useful approximation are known as linear-elastic or "Hookean" materials.
Mathematically, Hooke's law states that
where
- x is the displacement of the end of the spring from its equilibrium position;
- F is the restoring force exerted by the material; and
- k is the force constant (or spring constant).
Hooke's law is named after the 17th century British physicist Robert Hooke. He first stated this law in 1676 as a Latin anagram,[1] whose solution he published in 1678 as Ut tensio, sic vis, meaning, "As the extension, so the force".When this holds, the behavior is said to be linear. If shown on a graph, the line should show a direct variation. There is a negative sign on the right hand side of the equation because the restoring force always acts in the opposite direction of the displacement (for example, when a spring is stretched to the left, it pulls back to the right).
Examples of scalars
Some examples of scalars include the mass, charge, or the temperature, or electric potential at a point inside a medium. The distance between two points in three-dimensional space is a scalar, but the direction from one of those points to the other is not, since describing a direction requires two physical quantities such as the angle on the horizontal plane and the angle away from that plane. Force cannot be described using a scalar, since force is composed of direction and magnitude, however, the magnitude of a force alone can be described with a scalar, for instance the gravitational force acting on a particle is not a scalar, but its magnitude is. The speed of an object is a scalar (e.g. 180 km/h), while its velocity is not (i.e. 180 km/h north).
Examples of scalar quantities in Newtonian mechanics:
FBR
The fast breeder or fast breeder reactor (FBR) is a fast neutron reactor designed to breed fuel by producing more fissile material than it consumes. The FBR is one possible type of breeder reactor.
The reactors are used in nuclear power plants to produce nuclear power and nuclear fuel.
As of 2006, all large-scale FBR power stations have been liquid metal fast reactors (LMFBR) cooled by liquid sodium. These have been of one of two designs:
- Loop type, in which the primary coolant is circulated through primary heat exchangers external to the reactor tank (but within the biological shield owing to the presence of radioactive sodium-24 in the primary coolant).
- Pool type, in which the primary heat exchangers and circulators are immersed in the reactor tank.
Raman scattering
Raman scattering or the Raman effect (pronounced /ˈrɑːmən/) is the inelastic scattering of a photon. Discovered by Sir Chandrasekhara Venkata Raman in liquids[1] and by Grigory Landsberg and Leonid Mandelstam in crystals
In 1922, Indian physicist C. V. Raman published his work on the "Molecular Diffraction of Light," the first of a series of investigations with his collaborators which ultimately led to his discovery (on 28 February 1928) of the radiation effect which bears his name. The Raman effect was first reported by C. V. Raman and K. S. Krishnan, and independently by Grigory Landsberg and Leonid Mandelstam, in 1928. Raman received theNobel Prize in 1930 for his work on the scattering of light. In 1998 the Raman Effect was designated an ACS National Historical Chemical Landmark in recognition of its significance as a tool for analyzing the composition of liquids, gases, and solids
Saturday, November 7, 2009
Coriolis effect
In physics, the Coriolis effect is an apparent deflection of moving objects when they are viewed from a rotating reference frame.
Newton's laws of motion govern the motion of an object in an inertial frame of reference. When transforming Newton's laws to a rotating frame of reference, the Coriolis force appears, along with the centrifugal force. If the rotation speed of the frame is not constant, the Euler force will also appear. All three forces are proportional to the mass of the object. The Coriolis force is proportional to the speed of rotation and the centrifugal force is proportional to its square. The Coriolis force acts in a direction perpendicular to the rotation axis and to the velocity of the body in the rotating frame and is proportional to the object's speed in the rotating frame. The centrifugal force acts outwards in the radial direction and is proportional to the distance of the body from the axis of the rotating frame.
These three additional forces are termed either inertial forces, fictitious forces or pseudo forces. These names are used in a technical sense, to mean simply that these forces vanish in an inertial frame of reference.
Thursday, October 29, 2009
Cyclotron
A cyclotron is a type of particle accelerator. Cyclotrons accelerate charged particles using a high-frequency, alternating voltage (potential difference). A perpendicular magnetic field causes the particles to spiral almost in a circle so that they re-encounter the accelerating voltage many times.
Ernest Lawrence, of the University of California, Berkeley, is credited with the development of the cyclotron in 1929, though others had been working along similar lines at the time
Atomic Clock
An atomic clock is a type of clock that uses an atomic resonance frequency standard as its timekeeping element. They are the most accurate time and frequency standards known, and are used as primary standards for international time distribution services, and to control the frequency of television broadcasts and GPS systems.
In August 2004, NIST scientists demonstrated a chip-scaled atomic clock.[8] According to the researchers, the clock was believed to be one-hundredth the size of any other. It was also claimed that it requires just 75 mW, making it suitable for battery-driven applications. This device could conceivably become a consumer product.
In March 2008, physicists at NIST demonstrated optical atomic clocks based on individual mercury and aluminum ions. These two clocks are the most accurate that have been constructed to date, with neither clock gaining nor losing at a rate that would exceed a second in over a billion years.
Units
| Parameter: | Metric Unit | British Units |
|---|---|---|
| time duration, delay | second * s | second, minute hour, day |
| frequency | hertz 1/s | cycle per second |
| length distance, displacement | meter 1/299 792 458 light sec m | inch, foot, yard rod, chain, furlong, mile |
| velocity, speed rate of change of position | meter per second m/s | foot per second mile per hour, knot |
| acceleration rate of change of velocity | meter per second squared m/s2 | foot per second squared |
| mass quantity of material | kilogram * kg | ounce, pound, slug, ton |
| force push, pull, or weight | newton kg m/s2 | pound-force |
| impulse force times time | newton second kg m/s | pound-force second |
| momentum mass times velocity | kilogram meter per second kg m/s | pound foot per second |
| work, energy force times distance | joule (pronounced "jewel") = one newton meter kg m2/s2 | foot pound-force |
| power rate of doing work | watt = one joule per second kg m2/s3 | foot pound-force per second horsepower |
| area size of a surface | square meter m2 | square foot, square yard acre, square mile |
| pressure force per unit area | pascal newton per square meter kg/m s2 | pound-force per square inch |
| volume, capacity | cubic meter (stere) m3 | pint, quart, gallon cubic foot, cubic yard |
| density, heaviness | grams per cubic centimeter g/cm3 | pounds per cubic foot |
| Parameter: | Metric Heat Unit | British Heat Unit |
|---|---|---|
| heat energy | joule, j calorie, Calorie 1 cal = 4.186 joules 1 Cal = 4186 joules | British Thermal Unit, BTU |
| temperature change | kelvins, K * | Fahrenheit degree, Fº |
| temperature | kelvins, K | degrees Fahrenheit, ºF |
| Parameter: | Metric Light Unit |
|---|---|
| luminous intensity | candle * |
| luminous flux | lumen one candle produces 4 pi lumens |
| illumination | lux lumen per square meter |
| focus | diopter reciprocal meters |
| astronomical distance | parsec |
| Parameter: | Metric Electrical Unit |
|---|---|
| electric charge | coulomb * 96,500 coul = 1 faraday faraday = 1 mole of electrons |
| electromotive force (EMF) | volt (joule per coulomb) |
| capacitance | farad (coulomb per volt) |
| electric current | ampere (coulomb per second) |
| electric energy | joule (watt second) (newton meter) KWH = 3,600,000 joules |
| electric power | watt (joule per second) |
| electrical resistance | ohm (volt per ampere) |
| electrical conductivity | siemens (coulomb per joule) (ampere per volt) |
| electrical field strength | volts per meter |
| electromagnetic inductance | henry (pl. henrys) |
| magnetic field intensity | oersted (formerly the gauss) |
| magnetic flux | weber (108 maxwells) |
| magnetic flux density | tesla weber per square meter |
| magnetomotive force | gilbert |
There's more:
Fluorescence
Fluorescence is the emission of visible light by a substance that has absorbed light of a differing, usually invisible, wavelength. Absorption of a photon triggers the emission of a photon with a longer (less energetic) wavelength. A shorter wavelength emission is sometimes observed from multiple photon absorption. The energy difference between the absorbed and emitted photons ends up as molecular rotations, vibrations or heat. Sometimes the absorbed photon is in the ultraviolet range, and the emitted light is in the visible range, but this depends on the characteristics of the particular fluorescent substance.
Here High Energy Photon is absorbed and low energy photon is emitted
Subscribe to:
Posts (Atom)