Category Science

Why does the rising or setting sun appear bigger?

                We know that the sun is much bigger than the earth but appears very small because it is very far from our planet. The sun is about 150 million kilometres from the earth. When the sun is overhead its distance is 6000 kilometres less than the rising and the setting sun, which is equal to the diameter of the earth. The distance of 6000 kilometres is negligible as compared to 150 million kilometres and would not make any difference in the size of the solar disc. In case of any difference, the sun at noon would have been looked a bit bigger than that of the size of rising and setting sun. Do you know why do we observe exactly the opposite effect? 

 

 

               The bigger solar disc seen in the morning or in the evening is an optical illusion. If you take a photograph of the morning, noon and evening sun, then you will see that the solar image is of the same size. The optical illusion works for the lunar disc also, and because of this, the rising moon appears quite big.

               The reason for this optical illusion is probably because we tend to compare the size of the rising or the setting sun with earthly objects. When we see a tree, or a building or a ship near the solar disc then the size of the sun appears to be big. At noon, when the sun is overhead, we are not able to compare it with any close by object near the sun. In short, we can say that the bigger appearance of the rising and the setting sun is nothing but just an illusion. In fact, the sun’s size always remains the same.

Can fresh water be obtained from the Sea?

               We all know that sea water is salty. It  contains many minerals which make it salty. Salinity of sea water varies a great deal in different parts of the ocean. On an average, there are 35 parts of salt to every 1000 parts of sea water. Now the question is whether it is possible to remove salt from the sea water and make it drinkable.

               There are several methods to make the sea water drinkable. One method is distillation. In this, sea water is boiled and the steam is condensed into water. Water gets vaporized leaving behind the salt. Water so obtained is fresh and good for drinking. For this purpose, nuclear energy or solar energy is used.

               In another method, electrical energy is used. Here, an electrical current is passed through the sea water. The electric current causes positive salt ions to flow in one direction and negative ions in the other. In fact, about 3.5 per cent of sea water consists of dissolved elements. These elements are sodium and chlorine which together form salt. On passing electricity, sodium ions move towards cathode and chlorine ions towards anode. This way, salt is removed from the water and water becomes worth drinking.

               In another method, some special types of membranes are used to purify water. There are thin membranes which let pure water through while blocking the flow of salts. Water filtered with these membranes becomes pure.

                By another method, the sea water is simply frozen. This process extracts salt from the water. After the salt has been separated from the ice, the ice is melted, giving fresh water. But this process is only for limited purposes.

               One of the best methods of obtaining fresh water is called multi-stage flash distillation. In it sea water vaporizes rapidly several times, each time in a higher vacuum and at a lower temperature.

               The world is now faced with an ever-increasing demand for fresh water.

               Scientists in many countries of the world are developing new methods for obtaining fresh water from the sea. In Israel, for example, and other oil-producing countries in Middle East, it has become worthwhile to build big plants to distill fresh water from the sea. However, due to high cost in processing, it is not still considered economically viable as an alternate source of fresh water. The research on the subject is still in experimental stage. 

Where is the world’s oldest underground railway?

               The world’s first underground railway was built in London city. Once the route was planned, a great trench was cut along the streets. Then the railway tracks were laid and the trench was covered over again, to restore the road and create a railway tunnel underneath. This method of tunnel making is called ‘cut and cover’.

               The original route of the London underground railway was nearly four miles long from Paddington Station to Farringdon Street in London. It was opened on 10th January 1863. The first trains were hauled by steam engines and the smoke in the tunnels caused discomfort. But this being the world’s first under-ground railway, it was a cause of great excitement. Today, the most extensive underground railway system in the world is in London.

               In 1890, a deep tunnel railway was also built in London through which electric trains could run. The earlier trains did not have any windows as they were thought to be unnecessary if the train was only to travel through a tunnel. The deepest underground point on the railway line is 67.3 m deep near Hampstead. The longest single journey is from Epping to West Ruislip which is 54.9 km long.

               Many other countries of the world also have underground railways. In Paris an underground railway was opened in 1900. In the United States of America the first practical subway line was constructed in Boston between 1895 and 1897. New York City opened the first underground railway in 1904, now the largest system in the world. The world’s busiest ever metro system has been the Greater Moscow in Russia (Opened in 1935).

               In Canada, Toronto opened a subway in 1954. In Japan, the Tokyo subway was opened in 1927. India’s first underground railway was inaugurated in Calcutta in 1985. This has relieved pressure on Calcutta’s traffic problems to a considerable extent.

               Construction of underground railways is a very complicated process. Normally deep trenches are dug by the side of main roads to lay rails. The walls of these trenches are made of bricks and are covered with strong steel beams to make the roofs. The trains run underground and other vehicles above them on the roads. 

Why do Mars appear red?

               We know that there are nine planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. In terms of distance from the Sun, Mars is the fourth planet. It is the outermost of the terrestrial planets and is often called the Red Planet. Do you know why?

               We know that Mercury is the planet closest to the Sun. It rises and sets almost with the Sun. Therefore, we can see it either before sunrise or after sunset. Similarly, we see Venus either sometime before sunrise or sometime after sunset (dusk). But Mars can be seen clearly only for a month or two every other year. Among all the planets Mars is next only to Venus in brightness. Also it is very striking not because of its brightness but for its reddish-yellow colour. To study Mars, man has sent many space probes. These spaceships have provided us with many valuable facts about it. In 1976, the American space probes Viking I and II landed on the Martian surface. They gave valuable information about the atmosphere of Mars. It has been found that the atmosphere of Mars contains 1 to 2 percent argon, 2 to 3 percent nitrogen, 95 percent carbon-dioxide and 0.3 percent oxygen.

               The surface of Mars appears to be made up of bright and dark areas. About 70 percent of the Martian surface is found reddish and yellowish which gives the planet its characteristic colour. These areas constantly change shape. It has many rocks containing rusty iron and is covered with reddish-brown deserts. The winds blow at very high speeds of about 400 km/hr over Mars and create heavy storms in Martian deserts. The storms raise a lot of red dust in the atmosphere. Since Mars has a weak gravitational pull, these dust particles remain in the atmosphere for weeks together. And so Mars, because of its red dusty surface and the dust particles in the atmosphere, appears reddish orange to us.

What is Artificial Intelligence?

               When we speak of intelligence we refer to the natural intelligence of people which means their inherent mental ability. But artificial intelligence is the intelligence of machines that can think like human minds. Of late, scientists have developed computers which can perform tasks that require intelligence. The successful performance of such tasks which need some thinking and analysis has again generated the old debate whether machine is superior to man or vice versa?

               Nowadays machines can easily recognize and read printed words. Autopilots, which are computerized machines, can fly aircrafts. These intelligent machines can also recognize and respond to sound and voice and also learn to rectify the mistakes committed. Even computers can play chess so brilliantly that they sometimes outwit the human beings. The whole world was stunned when an IBM computer defeated the world champion Gary Kasparov in a game of chess. But does this mean that artificial intelligence is superior to the natural intelligence of man?

               A computer carries out a series of operations as per the programs developed by computer programmers. This means that the human intelligence works behind the artificial intelligence of machines. Artificial intelligence has its limitations as it depends on the amount of stored information in it to make a decision whereas the natural intelligence is not handicapped by any such limitations.

               Now research is underway to create sound links with computers so as to enable them to recognize human speech and thus receive the feedback orally rather than inserting the instructions through the keyboard. This development of direct interaction with machines or computers would be another milestone in the field of artificial intelligence.

               Now artificial intelligence research covers the areas of planning, language understanding, and pattern recognition and knowledge representation. But whether it can ever surpass the natural intelligence of man, only the future can say.

 

Pandurang Sadashiv Khankhoje

Pandurang Sadashiv Khankhoje

                Pandurang Sadashiv Khankhoje (7 November 1884 – 22 January 1967) was an Indian revolutionary, scholar, agricultural scientist and historian who was among the founding fathers of the Ghadar Party.

                Khankhoje was born in November 1884 to a Marathi family at Wardha, where his father worked as a petition-writer. Young Khankhoje spent his childhood in Wardha, where he completed his primary and middle school education before moving to Nagpur for higher education. He was at the time inspired by the nationalist work of Bal Gangadhar Tilak.

               At some time in the first decade of the 1900s, Khankhoje left India on a voyage that ultimately saw him settle in the United States. Here he enrolled in the Washington State College (now called Washington State University), graduating in 1913. His earliest nationalist work abroad dates back to the time around 1908 when he, along with Pandit Kanshi Ram founded the Indian Independence League in Portland, Oregon. His works also brought him close to other Indian nationalists in United States at the time, including Taraknath Das.

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