Showing posts with label approximately. Show all posts
Showing posts with label approximately. Show all posts

Monday, February 8, 2010

Faraday

LinkGrand.com

the quantity of charge carried by one mole of electrons (which is approximately equal to Avogadro's constant x the charge on an electron), which has the value 9.6487 x 104 coulombs. It was named after Michael Faraday (1791-1867), a British scientist whose contributions to physics and chemistry include ELECTROMAGNETIC INDUCTION, electrolysis and MAGNETIC FIELDS.

Taken from Dictionary of Science

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Michael Faraday, FRS (22 September 1791 – 25 August 1867) was an English chemist and physicist (or natural philosopher, in the terminology of the time) who contributed to the fields of electromagnetism and electrochemistry.


Faraday studied the magnetic field around a conductor carrying a DC electric current, and established the basis for the electromagnetic field concept in physics. He discovered electromagnetic induction, diamagnetism, and laws of electrolysis. He established thatmagnetism could affect rays of light and that there was an underlying relationship between the two phenomena. His inventions of electromagnetic rotary devices formed the foundation of electric motor technology, and it was largely due to his efforts that electricity became viable for use in technology.


As a chemist, Faraday discovered benzene, investigated the clathrate hydrate of chlorine, invented an early form of the bunsen burner and the system of oxidation numbers, and popularized terminology such as anode, cathode, electrode, and ion.


Although Faraday received little formal education and knew little of higher mathematics, such as calculus, he was one of the most influential scientists in history. Some historians of science refer to him as the best experimentalist in the history of science.The SI unit of capacitance, the farad, is named after him, as is the Faraday constant, the charge on a mole of electrons (about 96,485 coulombs). Faraday's law of induction states that a magnetic field changing in time creates a proportional electromotive force.


Faraday was the first and foremost Fullerian Professor of Chemistry at the Royal Institution of Great Britain, a position to which he was appointed for life.


Albert Einstein kept a photograph of Faraday on his study wall alongside pictures of Isaac Newton and James Clerk Maxwell.


Faraday was highly religious; he was a member of the Sandemanian Church, a Christian sect founded in 1730 which demanded total faith and commitment. Biographers have noted that "a strong sense of the unity of God and nature pervaded Faraday's life and work."


Taken from Wikipedia



Wednesday, January 13, 2010

Magellanic Clouds


two separate GALAXIES, detached from the Milky Way, which appear, from the southern hemisphere, as patches of light. The Large Magellanic Cloud is approximately 170,000 LIGHT YEARS away and the Small Magellanic Cloud about 210,000 light years away. They contain a few thousand million stars.

Taken from Dictionary of Science

Galactic Rotation


the rotation of the GALAXY, and all its gas, stars and dust, which increases towards its centre. The rotation near the SUN is approximately 250 kms-1 and to make one galactic orbit takes the Sun in the region of 250 million years.

Taken from Dictionary of Science

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The rotation curve of a galaxy can be represented by a graph that plots the orbital velocity of the stars or gas in the galaxy on the y-axis against the distance from the center of the galaxy on the x-axis. Stars revolve around the center of galaxies at a constant speed over a large range of distances from the center of the galaxy. Thus they revolve much faster than would be expected if they were in a free Newtonian potential. The galaxy rotation problem is this discrepancy between the observed rotation speeds of matter in the disk portions of spiral galaxies and the predictions of Newtonian dynamics considering the visible mass. This discrepancy is currently thought to betray the presence of dark matter that permeates the galaxy and extends into the galaxy's halo. An alternative explanation is a modification of the laws of gravity, such as MOND (Modified Newtonian Dynamics).

Taken from Wikipedia