Paul Cooney
Fiber Optics

In recent years, a new method of transporting data has rapidly transformed the communication highway. Through the use of optical fibers, it is now possible to send transmissions over longer distances and at higher data rates than previous forms of communications. In contrast to metal wires, these glass or plastic fibers transmit signals with less loss and are also immune to electromagnetic interference. Simply put, a fiber optic is light that is sent through fibers no larger than human hair; however there were some problems that had to be overcome to accomplish this. Despite the challenges, there was nothing some good physics could not resolve.

One of the major theories behind fiber optics is the physics of total internal reflection. This is a vital component of making the fiber successfully “hold” onto its signal. As light is shot through the optical fiber, it is important to keep the light in the “core” of the optical fiber. Total internal reflection can only be described as an optical phenomenon, one which occurs as light strikes a boundary of a medium at an angle slightly larger than the critical angle, with respect to the surface. The critical angle of light is the angle of incidence above which the total internal reflection occurs. All materials have different refractive indices, and each act differently when light hits the surface of the material/medium. Upon impact, some of the light is partially reflected, and some of the light is refracted at the boundary of the new medium.
The key to ensuring that light is kept within the core of the fiber is the angle of incidence the light has. If this angle is greater than the critical angle, then the light will no longer cross the boundary and instead be completely reflected back internally. This is only possible when light travels from a medium with a higher refractive index to one with a lower index. Check out this picture to see exactly just what internal reflection is:

The blue line, representing a certain light wave, does not pass through the medium. Instead, it is completely refracted back. Now picture this event occurring within a tiny fiber, bouncing off every “wall” as it travels the length of the fiber. This is basically how it goes down. Here is another picture to give you a better idea of what really happens in a fiber.

The type of fiber shown above is called a multimode fiber; rays of light are guided along the fiber core by a previously discussed idea, total internal reflection. The rays of light meet the core-cladding boundary as seen in the picture at a rather high angle, actually greater than the critical angle. This allows for the rays to be completely reflected.
Compared to electrical cables, optical fibers are far greater in their performance of transmitting information. They are commonly used as a medium for telecommunication as well as networking. Due to their small size, fibers can be flexed to conform to space requirements such as in office buildings. Each individual fiber can carry in excess of two independent channels, with each channel having a different wavelength. Constructed out of glass or plastic, the fibers are not susceptible to ignition, and therefore can be used in various environments where as electrical cables would present a danger. Long range telecommunications employ the use of glass fibers, because they have a lower optical attenuation. In conclusion, fiber optics have paved the way for faster telecommunications and data sharing,



Works Cited

McPherson , Emily . "Homework Help: Science: Physics: Fiber Optics." Jiskha Homework Help. 11 Feb 2008 .

"Optical Fiber." Wikipedia. 2008. Wikipedia. 11 Feb 2008 .

"Total internal reflection." Wikipedia. 2008. Wikipedia. 11 Feb 2008 .

Paul Cooney
AP American
Mr. DeCarlo
5 April 2007


LAD 30-Brown vs. Board of Education

Due to the racial segregation in the early 1950’s, blacks often times did not receive the same privileges as whites. In Topeka, Kansas, the right being denied to a black third-grader named Linda Brown was the right to attend a school close to where she lived. At the time, little Linda had to walk one mile to and from school every day through a railroad switchyard, subjecting herself to grave danger. Meanwhile, there happened to be an all with school just seven blocks from her house, but was denied admittance. With the aid of the NAACP, black parents requested an injunction that would not allow the segregation of Topeka's schools. The court agreed upon the fact that segregation of the schools affected the children’s motivation to learn, however The U.S. District Court for the District of Kansas ruled in favor of “separate but equal.” The case was then appealed to the Supreme Court, resulting in the desegregation of public schools. It was decided that separated educational facilities are inherently unequal; the desegregation did not apply to other public areas such as restaurants or pools.

Paul Cooney
AP American
Mr. DeCarlo
25 March 2007

LAD #29-The Truman Doctrine

On March 12th, 1947, Harry S Truman shifted America’s foreign policy to the containment of Communism. He did this by proclaiming that the United States should aid Greece and Turkey economically and militarily, in an effort to diminish the appealing aspects of Communism to the poor. At the time, Greece was without adequate funds due to the civil war in the country against Communist insurgents. They needed to resume their purchases of food, clothing, fuel and seeds to survive. Great Britain had previously been providing the necessary aid to Greece, but when funds ran short, they came to the United States desperately asking for help. If Greece and Turkey were to fall into Communist control, it would ripple all through the region. The Greek army was weak, poorly equipped, and was having trouble resorting governmental power over the country. In his speech, Truman makes a point of stating that “there is no other country to which democratic Greece can turn.” This emphasizes the obligation of the United States to side with the democratic country in their time of need. Turkey also needed help; if Turkey’s national integrity was to survive, it needed financial aid and the United States was the only country they could turn to.

Paul Conney
Mr. DeCarlo
AP American
6 March 2007

LAD 26-Schenck vs. US

In 1919, the First Amendment to the Constitution was challenged in the court case Schenck vs. US. Charles Schenck, a socialist, had circulated a flyer urging people to resists the draft during WWI. The flyer cited the thirteenth amendment’s provision against “involuntary solitude,” trying to get men to oppose the draft by peaceful resistance. He was convicted of violating the Espionage Act of 1917 by attempting to cause insubordination in the military and to obstruct recuitment.

Paul Cooney
AP American
Mr. DeCarlo
6 March 2007

LAD 28- FDR’s First Inaugural Address

When FDR was inaugurated on March 4, 1933, it seemed as if the American economic system was about to collapse. This was a real fear for all Americans, and FDR addressed the nation in his first inaugural on this issue. The new President proclaimed that the only thing people had to fear was fear itself, and that the primary task at hand was to put people to work. This was to be accomplished by the direct employment of citizens by the government, acting quickly, and the collaboration of relief programs nation wide. Banks were also subject to FDR’s new plans, and two days after his first inaugural he closed all banks, restricting the export of gold or the redemption of currency in gold. He called upon the nation to stick together, reminding them that they had not failed; simply “They have asked for discipline and direction under leadership,” which is what FDR was planning to provide.

Paul Cooney
AP American
Mr. DeCarlo
6 March 2007

LAD 27-Kellogg-Briand Peace Pact

This was an international treaty, including participation from over ten delegates, "providing for the renunciation of war as an instrument of national policy." Essentially it’s goal was to outlaw war, renouncing war as an instrument of national policy. It outlawed aggression, not a nation’s self-defense, and contained no enforcement provisions. The treaty proved to be ineffective, as cited in the actions of Japan in the Japanese invasion of Manchuria in 1931.

Paul Cooney
AP American
Mr. DeCarlo
5 February 2007


LAD 24- The Clayton Antitrust Act (1914)

This Act was created to fix the problems in the Sherman Anti-Trust Act. Some of the revisions outlined in the Clayton Antitrust Act were: price discrimination, changes in merger laws, sales conditions, and ownership laws. If price discrimination lessens the competition, or beings to create a monopoly in any line of commerce, it is illegal. The mergers and acquisitions executed by a company may not lessen competition, nor may the buyer deal with the seller’s competitor. These revisions primarily dealt with unfair competition created by the outlined situations, all of which were made illegal to further help the consumer and the small businesses. Probably the most significant section in the Clayton was the Act Section 8; codified at U.S.C. § 19. This forbade any single person from being the director of two or more competing business, to avoide monopolies.

Paul Cooney
AP American
Mr. DeCarlo
4 February 2007


LAD 23-Keating-Owen Child Labor Act of 1916

The child labor act manipulated Federal jurisdiction, by stating that goods transferred across state lines must be manufactured by children following the specified conditions in the act. The age and hours of work were specified, limiting the brutal work days for young children. The Attorney General, the Secretary of Commerce and the Secretary of Labor were given the responsibly of publishing regulations under the act, and anyone instructed by the Secretary of Labor through proper enforcement has the right to inspect any place where goods are made or stored for interstate commerce. If persons were found to be violating the Act, they were charged with fines and possible imprisonment, based upon what the court rules. The Keating-Owen Child Labor Act did not last long, as the Supreme Court intervened during the case of Hammer v. Dagenhart, and the Act was ruled unconstitutional.