My Science School

            Sao Tome and Principe is a Portuguese-speaking island nation in the Gulf of Guinea, off the western equatorial coast of Central Africa.

            The islands were uninhabited until their discovery by Portuguese explorers in the 15th century.

            Sao Tome and Principe got independence in 1975, and has since remained one of Africa’s most stable and democratic countries. In 1990, Sao Tome made changes to the constitution and embraced democratic reform. Sao Tome and Principe is the second-smallest African country after Seychelles. Until the recent discovery of oil in the Gulf of Guinea, which has had a significant impact on the country’s economy, its primary source of revenues came from its agriculture.

            The capital of the country, Sao Tome city, is situated in the north-eastern part of Sao Tome Island. The country’s closest neighbours are Gabon and Equatorial Guinea. The climate is basically maritime and tropical. The currency of the country is Dobra.

               Union of the Comoros is a sovereign archipelago island nation in the Indian Ocean east of Mozambique off the east coast of the African continent and west of the northern tip of Madagascar. Comoros is one among the smallest countries in the world and only has a total area of 1862 square kilometres.

               The Comoros consists of the three main islands: Ngazidja, Mwali, and Nzwani. The Union of the Comoros has three official languages — Comorian, Arabic and French. Capital and largest city is Moroni on Grande Comore.

               France colonized Mayotte in 1843 and by 1904 had annexed the remainder of the archipelago. In a 1974 referendum, 95 per cent of the population voted for independence. The exception was Mayotte. Today it remains a French overseas territory. Comoros is another one of the world’s poorest countries.

 

               This small- scenic island country located in the continent of Africa, Mauritius covers a total area of 2,040 square kilometres. It enjoys a tropical climate with clear warm sea waters, beaches, tropical fauna and flora complemented by a multi-ethnic and cultural population.

               Mauritius became an independent state in 1968, after gaining its sovereignty from France. The currency of Mauritius is the Mauritian Rupee. The capital of the country is Port Louis. The island of Mauritius is volcanic in origin and is almost entirely surrounded by coral reefs.

               Lake Vacoas, one of the main reservoirs, is the chief source of water. The most significant issues faced by the country currently are water pollution, and degradation of coral reefs.

               However, the country now boasts one of Africa’s highest per capita incomes, achieved through tourism.

               Mauritius is the only country in Africa where Hinduism is the largest religion. The government uses English as its main language.

               Located in the continent of Europe, Luxembourg became an independent state in 1867, after gaining its sovereignty from The Netherlands.

               Luxembourg shares land borders with 3 countries: Germany, Belgium, and France. Luxembourg is a constitutional monarchy and a prominent financial centre.

               Its capital, Luxembourg City, is, together with Brussels and Strasbourg, one of the three official capitals of the European Union and the seat of the European Court of Justice, the highest juridical authority in the EU.

               Luxembourg’s high-income economy has a solid growth, low inflation, and low unemployment. Its culture, people and languages are highly intertwined with its neighbours, making it essentially a mixture of French and Germanic cultures. This is emphasized by the three official languages, Luxembourgish, French, and German.

               The Independent State of Samoa (formerly known as Western Samoa) is located south of the equator, in the Polynesian region of the Pacific Ocean, about halfway between Hawaii and New Zealand.

               Samoa consists of two main islands Upolu and Savai’i and seven smaller islets.

               Upolu is where Samoa’s capital city Apia is located and home to nearly three-quarters of Samoa’s total population.

               The Lapita people discovered and settled the Samoan Islands around 3,500 years ago. They developed a unique Samoan language and Samoan cultural identity. Samoans consists of about 92.6 per cent of the total population.

               The Samoans are the second-largest branch of the Polynesians, a people occupying the scattered islands of the Pacific from Hawaii to New Zealand and from eastern Fiji to Easter Island.

              Most of the remaining Samoans are of mixed Samoan and European or Asian descent.

              The Independent State of Samoa’s currency is Tala. Samoan and English are the official languages.

 

            Cabo Verde, or Cape Verde, an island nation on an archipelago of volcanic origin in the Atlantic Ocean, approximately 570 kilometres off the north-western coast of Africa, about 600 km west of Senegal.

            The Republic of Cape Verde was uninhabited until the 15th century, when Portuguese explorers discovered and colonized the islands, establishing the first European settlement in the tropics. Cape Verde subsequently became a trading centre for African slaves and later an important coaling and resupply stop for whaling and transatlantic shipping.

            The country got its independence in 1975. Since the early 1990s, Cape Verde has been a stable representative democracy, and remains one of the most developed and democratic countries in Africa. The capital and largest city is Praia.

            Trinidad and Tobago is an island country in the southeastern West Indies. It consists of two main islands: Trinidad and Tobago and several smaller islands.

            Trinidad and Tobago is one of the wealthiest countries in the Caribbean. It has large reserves of oil and gas. Many European powers colonized this island nation. Trinidad and Tobago became an independent state in 1962, after gaining its sovereignty from the United Kingdom.

            The capital of Trinidad and Tobago is Port of Spain, located on the north western coast of Trinidad. The currency of Trinidad and Tobago is the Trinidad and Tobago dollar. It is recognized by the World Bank as a high-income economy. Unlike most of the English-speaking Caribbean, the country’s economy is primarily industrial. The language spoken is English along with many vernaculars. Cricket is the national sport of the country.

 

 

 

 

How can a train float in the air?

Some experimental trains have been made to float a few centimeters above the ground by using a system of electromagnetic coils embedded in the track. Electromagnetic force can also be made to propel these trains. They have no wheels, so there is very little friction to waste energy. This magnetic propulsion system, which is completely silent, is called magnetic levitation.

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Magnetic motors

One of the most important uses of magnets is electric motors, which are used to power machines ranging from small toys to enormous railway engines. Video and audio tape recorders also depend on magnetism. Their tapes contain tiny metal particles that are magnetized by the recording heads. When played back, another part of the head decodes the magnetic patterns. The hard drive and floppy disks in a computer work in a similar way.

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Is the Earth a magnet?

The Earth is actually a huge magnet, with a magnetic north and a magnetic south pole. These poles are not quite the same as the true geographical poles, and they wander about slightly. There is geological evidence that the magnetic north and south poles sometimes switch their positions completely. The reasons for the Earth’s magnetism are not really understood, but it is thought to be due to the movement of electrical charges around the Earth’s core, which is probably mostly made up of iron.

The Earth’s magnetic field extends out into space. The Sun and the other planets in the Solar System also have magnetic fields. Some distant stars are known to have exceptionally powerful magnetic fields.

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Why do some metals stick to magnets?

An ordinary magnet has two poles, which are usually referred to as the North Pole and South Pole. Similar (like) poles repel each other, while unlike poles attract each other. You can easily see this happening if you hold two magnets close together. The north pole of one magnet will stick firmly to the south pole of the other magnet, while any two similar poles will be forced apart.

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What is magnetism?

Electrical currents are able to influence other electrical currents, and this force is called magnetism. Permanent magnets are materials in which this magnetic effect occurs because of the natural movement of electrons. Magnetism can also be caused by the flow of an electrical current through wires. The magnetic force of a magnet can repel (push) or attract (pull) another magnet or magnetic material.

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What are silicon chips?

A silicon chip is a tiny wafer of silicon (a semiconductor) on which a complete electronic device can be produced. An image is produced photographically and etched onto the chip, but it differs from a printed circuit in some important ways. The chip is often microscopically small and contains huge amounts of ‘wiring’. More importantly, part of the process allows other devices to be produced in the manufacturing process, such as tiny resistors and capacitors. So a silicon chip, or integrated circuit, which measures just a few millimeters across, is a complete electronic device.

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What is a printed circuit?

Any modern electrical device requires a huge number of connections to join together all the small components needed for it to work effectively. At one time these connections were made by wires that had to be soldered together. The wires have now been replaced by the printed circuit, which is effectively a picture of the wiring that works just as well.

A thin sheet of copper is attached to a special board made of insulating material. An image of the electrical circuit is then printed photographically onto the copper sheet. Chemicals are used to dissolve most of the copper, leaving behind a thin film of metal bands, to which all the necessary components can be attached. This process can be carried out automatically.

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What are radio waves?

Radio waves form part of the electromagnetic spectrum. They are not part of the visible spectrum of light, and they have even longer wavelengths than infrared radiation. Radio waves with the longest wavelengths are bounced off a layer high up in the Earth’s atmosphere, called the ionosphere. In this way radio messages can be bounced for very long distances. Radio waves with shorter wavelengths penetrate the Earth’s atmosphere completely and can be used to communicate with spacecraft.

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How does radio communication work?

Radio signals are transmitted using a carrier wave. A radio transmitter changes, or modulates, this radio wave in order to convey information. In AM radio the height of the carrier wave is altered according to the sound picked up by a microphone. In FM radio the frequency, or distance between the peaks in the radio wave, is changed. The radio receiver picks up these signals and amplifies and decodes them. If the signal is weak, AM radio sounds crackly. It is now being replaced by FM radio, which gives much clearer reception.

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