Monthly Archives: November 2010

Fundamentals of Pulsar Stars: How they Pulse?

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Pulsar Star

A pulsar is a Neutron Star which emits beams of radiation that sweep through the earth’s line of sight.

Like a black hole it is an end point to stellar evolution.

The “pulses” of high-energy radiation we see from a pulsar are due to a miss-alignment of the neutron star’s rotation axis and its magnetic axis. Pulsars pulse because the rotation of the neutron star causes the radiation generated within the magnetic field to sweep inand out of our line of sight with a regular period.

Pulsar Star

Pulsar Star

 

Short Question: What is the reason that Doppler Effect in light is symmetric but asymmetric in sound?

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Short Answer is summarised below:


In Sound, motion due to source affects the wavelength and the motion of the observer affects frequency. The relative velocity of the sound due to the motion of the observer is in the numerator. The relative velocity of sound due to motion of source is in denominator. The relative velocity of sound is not the same and constant.

In the case of doppler effect in light, first, the velocity of light is constant irrespective of the direction of motion of the observer or the source. There is no relative velocity.

Top 5 Scientists of Chemistry Killed or Injured by their Experiments

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Karl Scheele
(Died from Tasting his discoveries)

Scheele was a brilliant pharmaceutical chemist who discovered many chemical elements-Oxygen, Molybdenum, Tungsten, Manganese and Chlorine. He also discovered a process very similar to pasteurization. Scheele had the habit of taste testing his discoveries and, fortunately, managed to survive his taste-test of hydrogen cyanide HCN. But alas, his luck was to run out: he died of symptoms strongly resembling mercury poisoning.

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Robert Bunsen
(Blinded himself in one eye)

Robert Bunsen is probably best known for having given his name to the bunsen burner which he helped to popularize. He started out his scientific career in organic chemistry but nearly died twice of arsenic poisoning. Shortly after his near death experiences, he lost the sight in his right eye after an explosion of Cacodyl Cyanide. These being excellent reasons to change fields, he moved in to Inorganic Chemistry and went on to develop the field of spectroscopy.

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Sir Humphrey Davy
(A catalog of disasters)

Sir Humphrey Davy, the brilliant British Chemist and inventor, got a very bumby start to his science career. As a young apprentice he was fired from his job at an apothecary because he caused too many exploisons! When he eventually took up the field of chemistry, he had a habit of inhaling the various gasses he was dealing with. Fortunately this bad habit led to his discovery of the anesthetic properties of Nitrous Oxide. But unfortunately, this same habit led to him nearly killing himself on many ocassions. The frequent poisonings left him an invalid for the remaining two decades of his life. During this time he also damaged his eyes in a Nitrogen Trichloride Explosion permanently.

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Michael Faraday
(Suffered Chronic Poisoning)

Thanks to the injury to Sir Humphrey Davy’s eyes, Faraday became an apprentice to him. He went on to improve on Davy’s methods of electrolysis and to make important discoveries in the field of Electromagnetism. Unfortunately for him, some of Davy’s misfortune rubbed off and Faraday also suffered damage to his eyes in a nitrogen chloride explosion. He spent the remainder of his life suffering chronic chemical poisoning.

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Marie Curie
(Died of Radiation Exposure)

In 1898, Curie and her husband, Pierre, discovered radium. She spent the remainder of her life performing radiation research and studying radiation therapy. Her constant exposure to radiation led to her contracting leukemia and she died in 1934.

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Short Post: Mysteries of Universe! "Where did Galaxies come from?"

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Science has only recently been able to explain where the stars and planets came from. Now Scientists have turned their attention to a much bigger mystery, where did galaxies come from?

What is known is that galaxies are not scattered randomly throughout the space, rather they are found in clusters, known as “SUPER CLUSTERS”.

Scientists have two main theories to attempt to explain galaxy formation. First, the gas left over from the big bang clustered together to form galaxies, in which stars and planets were born.

Second is that gas from the bigbang created stars and planets all over the universe, and they migrated through gravity into galaxies.

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Why do the earth and other huge celestial bodies possess gravity?

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The Attraction between two bodies having mass has been defined as Gravitation. And as the word Gravitation suggests, it works on Point of Gravity of the bodies. From, as Newton Explained this attraction force,
F=GMm/r2
it is clear that this force depends upon the mass of two bodies (M &m, say) and the shortest distance (r) between bodies.

But the question, which influence mind that WHY do they perform this kind of attraction? As far I know, this is due to a ghost particle, which works on bodies, one to other and vice versa. This ghost particle has been named as Graviton. And the attraction has been explained on the basis of exchange of GRAVITONS similar to nuclear forces on one hand and on the curvature of the gravitational field on the other. We should remember that the concept of gravitons is just a fact. May be true or untrue.

As my best knowledge tells me, Graviton is a ghost (hypothetical) elementary particle that mediates the force of gravitation in the framework of quantum field theory.

If the concept of Graviton is true, then according to Quantum field theory:

¤The graviton must be massless because the gravitational force has unlimited range.

¤The graviton must have a spin of 2. This is because the source of gravitation is the stress-energy tensor , a second-rank tensor, compared to electromagnetism, the source of which is the four- current , a first-rank tensor.
Additionally, it can be shown that any massless spin-2 field would be indistinguishable from gravitation, because a massless spin-2 field must couple to ( interact with) the stress-energy tensor in the same way that the gravitational field does.
This suggests that if a massless spin-2 particle is discovered, it must be the graviton, so that the only experimental verification needed for the graviton may simply be the discovery of a massless spin-2 particle.

Gravitons are postulated because of the great success of quantum field theory (in particular, the Standard Model).
The hypothesis is that the gravitational interaction is likewise mediated by a – yet undiscovered – elementary particle, dubbed the graviton , instead of being described in terms of curved spacetime as in general relativity . In the classical limit , both approaches give identical results, which are required to conform to Newton’s law of gravitation.

Flow- StreamLine Transitional and Turbulent (FLUID MECHANICS)

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There are in general three types of fluid flow:-

~Laminar (Streamline)
~Turbulent
~Transient

Laminar flow (other names: Steady, Streamline flow)

In laminar flow, the velocity of moving fluid at any fixed point doesn’t change with time, either in magnitude or in direction.

Laminar flow generally happens when dealing with small pipes and low flow velocities.

Laminar flow can be regarded as a series of liquid cylinders in the pipe, where the innermost parts flow the fastest, and the cylinder touching the pipe isn’t moving at all. Shear stress depends almost only on the viscosity – μ – and is independent of density – ρ .
Example may regarded as The gentle flow of of water near the center of a quiet stream.
___
Turbulent flow

In turbulent flow vortices, eddies and wakes make the flow unpredictable.

Turbulent flow happens in general at high flow rates and with larger pipes. Shear stress for turbulent flow is a function of the density – ρ.
____
Transitional flow
Transitional flow is a mixture of laminar and turbulent flow, with turbulence in the center of the pipe, and laminar flow near the edges. Each of these flows behave in different manners in terms of their frictional energy loss while flowing, and have different equations that predict their behavior.

Turbulent or laminar flow is determined by the dimensionless Reynolds Number.
The Reynolds number is important in analyzing any type of flow when there is substantial velocity gradient (i.e. shear.) It indicates the relative significance of the viscous effect compared to the inertia effect. The Reynolds number is proportional to inertial force divided by viscous force .

The flow is
Laminar when Re < 2300
Transient
when 2300 < Re < 4000
Turbulent
when 4000 < Re.

Where Re denotes Reynolds' number.

Maximum worms swallow-Guinness World Record by Indian

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Indian Swallows WormsOn November 15 , 2003 an Indian man had set Guinness World Records for swallowing maximum worms.

Citizen of Chennai, India swallowed 200 worms in 20.22 seconds and smashed the previous record of 94 night crawlers in 30 seconds created by Mark Hogg of United States of America in 2000.