The Nile River

          The Nile River is the longest river in the world. Its length is around 4.180 miles. It flows through Uganda, Sudan and Egypt.

          It has two main tributaries. They are the Blue Nile and the White Nile. The White Nile stars in the Great Lakes region of central Africa. The Blue Nile begins at LakeT’ana in Ethiopia. These two rivers meet near Khartoum the capital city of Sudan.

          There is another shorter tributary. It’s Atbarah river, or also known as the Black Nile. However, this river flows only while there is rain in Ethiopia and dries very fast. The Nile River ends in Mediterranean Sea.

          The Nile River is important for agriculture, food, transportation and tourism. Farmers grow wheat, sorghum, citrus fruit, sugarcane and cotton along the Nile River, and they use the river to water their crops and plantation. People also fish this river. The river is used to transport goods to different places along its long path. The ships can travel up using the sail, and down using the flow of the river. Tourism is another main advantage of The Nile River. Some special places to visit are Aswan, Luxor, Giza, Cairo and Khartoum. People who like adventure will find traveling this river exciting.

Sources: http://en.wikipedia.org/wiki/Nile

Kangaroo (Macropus rufus)

          The Kangaroo is a common Marsupials from the islands of Australia and New Guinea. Marsupials are animals with pouch. They carry their babies in a pouch in the mother’s abdomen.

          Kangaroos have two strong legs with two long feet. They have a muscular long tail, large ears and a small head. They have short arms with clawed hands. The soft, woolly fur can be blue, grey, red, black, yellow or brown, depending on the species. Females have a pouch in which the young live and drink milk.

          These herbivores (plant-eats) eat grass, leaves, and roots. They swallow their food without chewing it. Kangaroos need little water; they can go for months without drinking, and they dig their own water wells.

          These shy animals live about 6 years in the wild and up to 20 in captivity. Most kangaroos are nocturnal (active at night). Kangaroos can hop up to 74 kilometers per hour and go over 9 meters in one hop.

Source: http://www.enchantedlearning.com/subjects/mammals/marsupial/                                                           

Radio

          Radio is a form of communication in which intelligence is transmitted without wires from one point to another by means of electromagnetic waves. Early forms of communication over great distances were the telephone and the telegraph. They require wires between the sender and the receiver.

          Radio, on the other hand, requires on such physical connection. It relies on the radiation of energy from a transmitting antenna in the form of radio waves. This radio waves, traveling at the speed of light (300.000 km/sec.) carry the information. When the waves arrive at a receiving antenna, the original information contained in the radio waves is retrieved and presented in an understandable form, such as sound from a loudspeaker.

          The principles of radio had been demonstrated in the early 1800s by scientists, such as Michael Faraday and Joseph Henry. They had individual induced (produced) a current in another wire that was not physically connected to the first.

          All radio programs or signals are transmitted within a broad spectrum of waves called the electromagnetic spectrum. This spectrum is responsible for producing a variety of waves, including those that can be detected by  man-made machines, such as X-rays. Radio waves are among the many types of electromagnetic waves that travel within the electromagnetic spectrum. Radio waves can be defined by their frequency (in hertz, after Heinrich Hertz, who first produced radio waves electronically), which is the number of times they pass through a complete cycle per second. Besides, we can define radio waves by their wavelength, which is determined by the distance (in kilometers) traveled from the crest of one wave to the crest of the next.

  Source: Encyclopedia of Knowledge

Television

          Television, or TV, is one of humanity’s most important means of communication. It brings pictures and sounds from around the world into millions of homes.

          People with a television set can sit in their house and watch the president makes a speech or visits a foreign country. They can see a war being fought, and they can watch government leaders try to bring about peace. Through television, viewers at home can see and learn about people, places, and things in far away lands. Television even takes viewers out of this world as the astronauts explore outer space.

          In addition to all these things, television brings its viewers a steady stream of programs that are designed to entertain. In fact, TV provides many more entertainment programs than any other kind of information media. The programs include action-packed dramas, light comedies, soap operas, sports events, cartoons, quizzes, variety shows, and motion pictures.

          More than 83 million homes in the United States -or 98% of all the countrys’ homes- have at least one television set. On the average, a television set is in use in each home for about 6 ¾  hours each day. As a result, television has an important influence on how people spend their time, as well as on what they see and learn. After they arrive from work, they usually watch TV. Then, the importance of television is proven.

  

Source: The New Book of Knowledge