Thursday, March 19, 2020

Charge Definition and Examples (Physics and Chemistry)

Charge Definition and Examples (Physics and Chemistry) In the context of chemistry and physics, charge usually refers to electric charge, which is a conserved property of certain subatomic particles that determines their electromagnetic interaction. Charge is a physical property that causes matter to experience a force within an electromagnetic field. Electric charges may be positive or negative in nature. If no net electric charge is present, the matter is considered to be neutral or uncharged. Like charges (e.g., two positive charges or two negative charges) repel each other. Dissimilar charges (positive and negative) attract each other. In physics, the term charge may also refer to color charge in the field of quantum chromodynamics. In general, charge refers to a generator of continuous symmetry in a system. Charge Examples in Science By convention, electrons have a charge of -1 while protons have a charge of 1. Another way of indicating charge is for an electron to have a charge of e and a proton to have a charge of e.Quarks possess what is known as color charge.Quarks may possess flavor charges, including charm and strangeness.Although hypothetical, magnetic charge has been postulated for electromagnetism. Units of Electric Charge The proper unit for electric charge is discipline-dependent. In chemistry, a capital letter Q is used to indicate charge in equations, with the elementary charge of an electron (e) as a common unit. The SI derived unit of charge is the coulomb (C). Electrical engineering often uses the unit ampere-hour (Ah) for charge.

Tuesday, March 3, 2020

How the Phoenicians Settled Carthage

How the Phoenicians Settled Carthage Phoenicians from Tyre (Lebanon) founded Carthage, an ancient city-state in the area that is modern Tunisia. Carthage became a major economic and political power in the Mediterranean fighting over territory in Sicily with the Greeks and Romans. Eventually, Carthage fell to the Romans, but it took three wars. The Romans destroyed Carthage at the end of the Third Punic War, but then rebuilt it as a new Carthage. Carthage and the Phoenicians Although Alpha and Beta are Greek letters that give us our word alphabet, the alphabet itself comes from the Phoenicians, at least conventionally. Greek myth and legend credit the dragon-teeth-sowing Phoenician Cadmus as not only founding the Boeotian Greek city of Thebes but bringing the letters with him. The 22-letter abecedary of the Phoenicians contained only consonants, some of which had no equivalent in Greek. So the Greeks substituted their vowels for the unused letters. Some say that without the vowels, it was not an alphabet. If vowels arent required, Egypt can also make a claim for the earliest alphabet. Were this the only contribution of the Phoenicians, their place in history would be assured, but they did more. So much, it seems as though jealousy prompted the Romans to set out to annihilate them in 146 B.C.  when they razed Carthage and were rumored to have salted its earth. The Phoenicians are also credited with: Inventing glass.The bireme (two tiers of oars) galley.The luxurious purple dye is known as Tyrian.Circumnavigating Africa.Navigating by the stars. The Phoenicians were merchants who developed an extensive empire almost as a by-product of their quality merchandise and trading routes. They are believed to have gone as far as England to buy Cornish tin, but they started in Tyre, in an area now part of Lebanon, and expanded. By the time the Greeks were colonizing Syracuse and the rest of Sicily, the Phoenicians were already (9th century B.C.) a major power in the middle of the Mediterranean. The principal city of the Phoenicians, Carthage, was located near modern Tunis, on a promontory on the Northern Coast of Africa. It was a prime spot for access to all areas of the known world. The Legend of Carthage After the brother of Dido (famed for her role in Vergils Aeneid) killed her husband, Queen Dido fled her palace home in Tyre to settle in Carthage, North Africa, where she sought to buy land for her new settlement. Coming from a nation of merchants she cleverly asked to buy an area of land that would fit within an ox hide. The local inhabitants thought she was a fool, but she got the last laugh when she cut the oxhide (byrsa) into strips to enclose a large area, with the sea coast acting as one border. Dido was the queen of this new community. Later, Aeneas, on his route from Troy to Latium, stopped in Carthage where he had an affair with the queen. When she found that he had abandoned her, Dido committed suicide, but not before cursing Aeneas and his descendants. Her story is an important part of Vergils Aeneid and supplies a motive for the hostility between the Romans and Carthage. At length, in dead of night, the ghost appearsOf her unhappy lord: the specter stares,And, with erected eyes, his bloody bosom bares.The cruel altars and his fate he tells,And the dire secret of his house reveals,Then warns the widow, with her household gods,To seek a refuge in remote abodes.Last, to support her in so long a way,He shows her where his hidden treasure lay.Admonishd thus, and seizd with mortal fright,The queen provides companions of her flight:They meet, and all combine to leave the state,Who hate the tyrant, or who fear his hate....At last they landed, where from far your eyesMay view the turrets of new Carthage rise;There bought a space of ground, which (Byrsa calld,From the bulls hide) they first inclosd, and walld.Translation from (www.uoregon.edu/~joelja/aeneid.html) of Vergils Aeneid Book I Vital Differences of the People of Carthage The people of Carthage seem more primitive compared to modern sensibilities than the Romans or Greeks for one main reason: They are said to have sacrificed humans, babies, and toddlers (possibly their first born to ensure fertility). There is controversy over this. Its hard to prove one way or the other since millennia-old human remains dont easily tell whether the person was sacrificed or died some other way. Unlike the Romans of their time, the leaders of Carthage hired mercenary soldiers and had a capable navy. They were extremely adept at trade, a fact that allowed them to rebuild a profitable economy even after the setbacks of military defeat during the Punic Wars, which included  a yearly tribute to Rome of almost 10 tons of silver. Such wealth allowed them to have paved streets and multi-story homes, compared with which proud Rome looked shabby. Source North African News Letter 1, by John H. Humphrey. American Journal of Archaeology, Vol. 82, No. 4 (Autumn, 1978), pp. 511-520