My Science School

            The 21st century would take people to a world of mechanical solidarity with courtesy from services like paging service, cellular telephone and Internet etc. Having acquainted ourselves with services like cellular telephone and Internet earlier, now let us discuss what paging service is all about.

            Paging is a one-way wireless communication providing instant access to the person being paged. One-way communication means that the subscriber only receives the message and can not communicate back instantly. The subscribers receive messages from anyone with access to a telephone. The modus operandi is as follow: The paging network of a particular region is co-ordinated by a ‘pagers exchange’ or network operator. Subscribers have a paging number assigned exclusively to them by the concerned network operator. The person who wants to send a message to a subscriber rings up the operator and leaves the message with him along with the subscriber’s paging number. Then the operator relays the message to the subscriber either directly or through any other regional operator. The message is then received by a small palm-size device called ‘pager’ kept by the subscriber with himself. An alarm sound from the device alerts the subscriber who then reads the message, flashed on the screen of the device. Some pagers also vibrate to alert the subscriber of an incoming message. The main advantage which a pager provides is that the subscriber receives the message wherever he may be since he carries the wireless device (pager) always with him.

            In India, as of now, the government has issued licenses to private operators to provide paging service to interested people and the number of subscribers is growing fast. As per current estimates, the running cost of a pager for monthly service would be around a couple of hundred rupees and a pager, at the moment, costs about a few thousand rupees. It is now the cheapest and most reliable one-way communication system available in the market today. Although its primary use is to get a message across fast, it has other potential uses such as getting across share market information by the business circles or to have latest cricket scores, for instance. The only demerit is that it provides only one-way communication as the receiver can not communicate back to the caller. 

          Electronic mail is a modern method of instant delivery of letters without the involvement of a postman. In this system of mailing, messages are sent with the help of a computer.

          In the electronic mail system a letter or any other document is typed and edited on a computer. It is then sent to the addressee through a computer network in the form of electrical signals. The addressee may be anywhere in the world but he should also have an electronic mail system. The contents of the transmitted letters or documents get displayed on the screen of the computer of the addressee. If he desires, he can get the message printed. If the addressee is absent, the transmitted matters will be automatically stored in the computer’s memory. When he returns the computer will give an indication that some mail is waiting for him.

          With the help of electronic mail system both typed and handwritten matters can be transmitted. Electronic mail is very fast and saves time and paper work but at present it is very costly. It needs a satellite, telephone and cable links with television, voice and computer data telecommunications. The electronic mail system has so far not been feasible for individual households. This system is being used by developed countries on a large scale.

          Email is widely used in Internet Services. It is also connected to other systems in which exchange of Email are being made effectively.

 

 

           In the 18th and 19th centuries, science fictions with an element of horror became quite popular with the masses. An Englishman named Horace Walpole first introduced horror as a permanent feature in most of his writings during the 1760s. Since then many writers started writing such stories including science fictions with amazing success. The Frankenstein’s monster is one such example that attained worldwide popularity.

           The story of Frankenstein was published in 1818 which had a scientific flavour with imagination. It is about the creation of a monster that ultimately destroys its creator. With its elaborate narrations of mystery, horror, outrage, madness and spirit of revenge - this character maintains the trend first started by Walpole. The basic idea behind the creation of the monster was to show the power of science - how a dead person becomes alive and the subsequent consequences of it. The trait induced in Frankenstein makes it a reactive and suffering creature that wavers between good and evil.

           But do you know who the creator of Frankenstein - the monster was? She was Shelly Mary Wollstonecraft, the daughter of William Godwin and second wife of the famous poet P.B.Shelly. She was born on 30 August 1797 in London. She spent much of her life editing her husband’s works after his death. Among the novels she wrote, the most famous was Life and Adventure of Castruccio.

           However, in spite of her many notable works, her name is mainly attached to the creature she portrayed in Frankenstein. This novel was transformed into feature films in many versions all over the world.

           Mary Shelly died on 1 February 1851 at the age of 54. 

               You will be surprised to know that there are some plants which catch and eat insects. Such plants are called insectivorous plants. Since they cannot prepare their own protein, they get it by eating insects and worms. Every plant of this kind uses it own technique for capturing insects. The leaves of these specialized plants are adapted to trap and digest insects - which supplement their food supply.

               One of the famous insectivorous plants is ‘pitcher plant’. The upper part of its leaf resembles a small pitcher. Its colour is very attractive. It contains a sticky liquid. The opening of the pitcher has small fibres which allow the insects to go inside but obstruct their coming out. On being attracted by the beautiful colour, when some insect enters this pitcher, it is unable to come out. It gets entangled in the juice of the pitcher and the plant produces certain enzymes and digests it. The ‘cobra plant’ of America which appears like a snake, also eats insects. It also has pitcher-shaped mouth.

               The ‘sundew plants’ have hair on their leaves. The tips of these hairs have droplets of a liquid which appear very attractive. As soon as some insect is attracted towards a leaf, these hairs bend forward, capture the insect and digest it with the help of their own juice. The digested flesh is absorbed through their leaves. After that the hairs again become normal.

               There is a plant called ‘venus-fly trap’ which is found in America. Its leaves have beautiful red coloured elevations on both sides. Whenever an insect sits on a leaf it closes like a fork and the plant digests the trapped insect by digestive juices. The ‘uticularia’ is a water plant. It is found all over the world. The roots of this plant which are submerged in water have bulbous bladders. When some aquatic insects enter the bladder, the hairs on its opening do not allow it to come out. The walls of these bladders give out digestive juices which suck the proteins out of the bodies of these small insects.

Similarly, a plant called ‘Indian pipe’ is found in the hills of Shimla. It also eats insects. In addition to these, there are many other insectivorous plants all over the world.

 

           The main device used to detect and locate objects like submarines and torpedoes under the sea water is called ‘sonar’. The word ‘sonar’ is an acronym for ‘sound navigation’ and ranging. This instrument is particularly useful in sea warfare. However, in peace time also, this is used in ships and submarines. It can locate objects at distances ranging from 100 metres up to 10 kms.

           Sonar mainly consists of two parts: the transmitter and the receiver. Both these parts are submerged in the sea water. The transmitter with the help of a transducer produces sound waves of high frequencies (5,000 to 300,000 hertz). These waves are called ultrasonic waves and cannot be heard by human ears. The transmitter transmits these waves in pulses in all the directions. Whenever these pulses strike some object inside the sea water, they get reflected. These reflected waves are received by the receiver. The time taken for the waves to reach the object and come back to the receiver is measured. Half of this time when multiplied by the speed of sound in sea water gives the distance of the object. This instrument contains a display device also, which accurately shows the distance and position of the object. 

           Sonar, however, is not a foolproof system. The sounds produced by some aquatic animals sometimes interfere with its transmissions and can be misleading about the position of the objects. The enemy submarines can be detected by this equipment and thus can be destroyed. These days there are various kinds of sonars being used for studying the objects inside water. Sonars also help in large scale fishing by locating those spots where large groups of fishes are present. Nowadays blue-green laser pulses are also being used for underwater detection of submarines and torpedoes. Laser based devices also work on the echo sounding principle just as a sonar works. 

 

          An obvious answer to this question is, “We cannot fly like birds because we do not have natural wings”. However, this answer does not explain this question fully because even if we attach artificial wings to our arms we cannot fly. Then how do the birds fly?

          Birds, of course fly with the help of their wings. They have very light frames. Their bones are also light. Moreover, they have air sacs which make them even lighter.

          Their muscles are quite strong in comparison to their body weight. They have a streamlined body which enables them to fly swiftly because air offers less resistance to streamlined objects. With the help of these muscles, they can easily fly with their wings.

          When a bird flaps its wings, it pushes the air down with its wings and rises above. Our bodies are heavier than those of birds. As such we would need enormously big wings. Again we do not have any air sacs and our muscles are not comparatively that strong. Hence we cannot flap the artificial wings.

          The birds with lighter bodies can fly more easily while the heavy birds face difficulties while flying. For example, the cock and peacock cannot fly very high. There are also birds like ostrich and penguin which are even heavier. They cannot fly at all. They can simply run. Thus we too cannot fly like birds even if we attach artificial wings to our arms.

 

          The rapid progress made in the field of Information Technology has revolutionized the world of communications. The world is gradually becoming a global village as interaction among people all over the world has become more frequent than ever before. The widespread and efficient use of computers in the field of telecommunications has made the world a smaller place to live in. ISD, FAX, Electronic Mail, Paging Service and now Internet - all are the gifts of this revolution. Internet has aroused much interest in recent days as it has become a very powerful medium of communication. But what is Internet and how does it operate?

          Internet is the world’s largest computer network. A computer network is basically a bunch of computers connected together in some way or other. It is just like a radio or TV network that links various radio or TV stations so that they can share a common programme. The major difference is that in TV networks the same information programme is sent to all stations whereas in computer network, each particular message is usually routed to a particular computer. Some computer networks consist of a central computer and a bunch of remote stations that report to it - for example, the centralized railway reservation system which links many terminal counters to a centralized computer. But other networks like the Internet permit any computer on the network to communicate with any other. Actually, the Internet is not really a network; it’s a network of networks - all freely exchanging information.

          Through Internet people from all countries can now share information, ideas, stories, data and opinions - the functions that are now generally carried out by letters, telephones and other modes of communications. It has become the fastest and most reliable way to move or exchange information. For example, during the 1991 Soviet coup, a tiny Internet network provided all the information to the rest of the world when all other communication systems were shut off. Medical researchers all over the world use the Internet to maintain data bases of rapidly changing data.

          The Internet facilities are provided through a large set of different services. Though to mention all the services would make the list exhaustive, some examples can be given. Electronic mail is the most widely used Internet service. Electronic mailing lists enable one to join in group discussions and meet people over the Net. Online conversation, Information retrieval, Bulletin boards and Games and gossip (challenging other players who can be anywhere in the world) are some other kind of Internet services.

          India’s access to the Internet has ushered in a new phase of computer communications in the country. Originally a small electronic community in the American Defence Department as a way for military researchers to contact with each other, Internet is now the world’s largest electronic network.

 

         Dragon is a legendary dreadful monster that never existed in reality. It is a mythical figure born out of people’s imagination long time ago. The belief in this creature apparently arose without the slightest knowledge on the part of the ancients about the gigantic, prehistoric dragon like reptiles.

         The word ‘Dragon’ comes from the Greek word ‘Drakon’ which was used for a large serpent. But dragon as a monster represents a huge, fire-breathing, bat-winged scaly lizard or snake with a barbed tail. In later period it mostly remained in the shape of a snake. In the Eastern world where snakes are large and deadly, a dragon symbolized evil. But in the West it was accepted both as a symbol of good and evil depending on circumstances. On the whole its evil reputation was stronger. The Christians and Jews perceived it as evil and dangerous. In Christian arts, dragon represented sin and sorrow.

          The form and appearance of dragon varied from place to place. The Babylonian dragon had four legs and the Biblical dragon was described as a many-headed creature, like the Greek Hydra. In wartimes it was used as an emblem representing valour. In the 20th century the dragon was officially incorporated in the armorial bearings of the Prince of Wales. The Chinese dragon, known as lungs, appears as the national symbol. The Japanese as well as Chinese dragons are usually wingless. Dragon images are also used in the north-eastern states of India as well as in Bhutan during different festivals.

         The Komodo dragons found in some Indonesian Islands are infact very large lizards. However, the dragons in the general sense still are mythical figures. 

          Money has always fascinated mankind from the time of Aristotle to the present day. Aristotle observed that man is a social being and establishes certain norms and regulations for their social interaction. Men employed money as a mode of exchange to facilitate such social dealings from their economical aspect.

          In the primitive societies, when people wanted to buy anything they had to give something else in exchange for it. For example, if a potter wanted to buy rice from a farmer, he offered him earthenware pots in exchange. The farmer would accept them because he needed pots. This was called the barter system which involved goods in exchange of goods. During those times goods served the purpose of money. But with the development of trade, the barter system could not meet the growing demands of a convenient exchange system for buying and selling. People started using token or symbolic goods in exchange all over the world. American Indians used beads of shells, Fijians used whale’s teeth and North Americans used tobacco in their exchange system. The Roman army men were provided salt for their services. But the topic of our interest is: when was coin first used as money? 

 

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