Welcome to the knowledge bank

Umbrella has always been one of the most useful ways of protection from the sun and the rain for those who have to work and walk outdoor in bad weather. The word umbrella comes from the Latin word ‘umbra’ meaning shade. But no one knows when or by whom the first umbrella was used. When the modern version of umbrella was invented, umbrellas were carried only by women, for they were not considered ‘manly’ enough to be used by men!

In very early times, in fact for thousands of years, umbrellas were used only for protection from the sun, rather than from the rain. It wasn’t until about 300 years ago that people began to use Waterproof umbrellas
in the rain.

Until around the year 1900 watches were carried in the pockets of vests or pants, and were tied
to the end. of a chain. Both the chain and the pocket were called the watch ‘fob’.

According to a popular story, a swiss watch maker saw a woman sittingin a park with a watch tied around her wrist, so that she could hold her child with both her hands free. He made a wristwatch in 1790, but no one really took notice of the great discovery and until about a century later the idea remained unused.

In 1914 a wristwatch was shown at an exhibition in Switzerland and people thought that it was “just a passing fancy”. Today, the same passing fancy” is the number one jewellery item in the world. Even an ordinary person can afford a wristwatch. About 80 million watches are made around the world each year!

Peice of metal shaped as fished used as a Compass in early China

South pointing spoon compas used by early Chinese for Feng Shui

It must have been very difficult for sailors and voyagers to travel through the vast seas without the help of modern gadgets to guide the way. In ancient times, sailors charted their course by the position of stars in the sky. In those days there was no such thing known as the compass. No one knows when or where the first compass was invented.

The earliest report of the use of compass appears in a Chinese book and the date given is the end of the 11th century A.D. The European ships used the compass in 1345. The early compasses consisted of an iron needle attached to a piece of wood or cork that floated in a bowl of water.

A really dependable compass was invented much later in the 19th century. But the compass is no longer used on ships - it has been replaced by a more efficient device called ‘gyrocompass’. This device reads the rotation of t_he earth and points to the true North Pole instead of the Magnetic North Pole

Modern magnetic Compass

                  

In the year 1795 a prize was announced by the French government for investing a way to preserve food for the  use of their army. A man named Francois Appert won the prize by devising a way to keep food fresh in sealed glass bottles by placing them in boiling water. But no one could explain why the food stayed fresh when treated that way, although it did not stray fresh for very long.

Again in 1829, William Underwood began selling bottled food in Boston. Ten years later, he used a tin-coated steel can instead of the glass bottle. The cans were assembled by workers and filled with food through a hole at the top. The hole was then sealed by a drop of solder.

In 1860, another American found a better process, to store food for longer periods. He heated the food inside cans at higher temperatures. Canned food has, since then, become one of the most popular way of preserving many food items.

Uranium is sometimes called the fuel source of the modern age. It has helped unlock the tremendous energy
hidden inside the atom. This atomic energy can be used for destructive purposes, but can also be used for generating energy for creative purposes. One kilogram of uranium can produce as much energy as nearly three
million kilograms of coal!

Pure uranium looks like silver or aluminium. But it is much heavier than other metals. A 0.3 cubic meter of uranium weights more than half a tonne.

Uranium is radioactive - this means its atoms break down slowly, releasing energy in the form of radiation. Some of its atoms are fissionable - which means they can be made to explode and break into two and in the process release vast amounts of energy. Because of these properties uranium is a very important metal. But extracting it from its ores to get it in its pure form is a complicated and expensive process.

 








The credit of inventing the gramophone record goes to Thomas Edison, the famous American scientist.

Edison, in 1877, noticed that a small disc inside a telephone receiver vibrated when the person at the other end of the line spoke. He then thought of attaching a tiny needle to the centre of the disc. The movement or force of the needle could tell him the amount of sound that was being sent out.

After many experiments he made a “phonograph or speaking machine” which had a cylinder covered with tin foil and turned with a hand crank.

In 1895, Emile Berliner brought the first gramophone record in the market. This was a disc instead of ea cylinder, made of Zinc coated with wax. To engrave the human voice, a needle was used which vibrated when a sound was made. It scratched a wiggly pattern in the wax. The record was then put into acid, which ate into the zinc where the needle had made a pattern. When another needle moved from the same path, the same voice was reproduced.

Although you cannot ‘see’ air, you need it for living. It has no colour, taste or smell. But it has weight and force and is made up of a mixture of a variety of individual gases. It surrounds or envelops the terrestrial globe to form the earth’s atmosphere.

A gas, or air which is a mixture of gases, does not have a definite shape or size but it fills up any available space. Actually, everything around us is made up of molecules - our bodies, rocks, plants, water, steam, gases all contain these tiny particles. The molecules in hard solid things are packed close together. The molecules in a liquid are less closely packed and can move about easily. But the molecules of a gas are thinly distributed and are free to move about freely.

The most important of all the gases present in the air is oxygen. We cannot live without this. We breathe air to give oxygen to our bodies to keep alive. But only about one fifth of the air is made up of oxygen. About four fifth is occupied by nitrogen. The‘ rest of the air is formed by a mixture of many gases. And due to pollution, the air that surrounds us also has dust particles and harmful matter in it. There is also some water vapour present in the air. But these things dust, water vapour, dirt are not really part of air it self. Although light and invisible, air has weight. This is why it is attracted and held to the earth by gravity and does not fly away into outer space.

Fire has been one of most useful and essential tool for mankind. It was the control of fire and making of tools that slowly led to better life for the cave-man. He found fire useful but was also scared of it. He started worshiping it.

Fire is a rapid and continuous chemical reaction accompanied by the emission of light and heat. The colour of the flame depends upon the material that is burning and the temperature it is reaching. In this chemical reaction two substances combine to form one or more new substances. The substances that we commonly use to make a fire are wood, coal, paper, petrol etc. Are mainly made up of carbon and hydrogen.

To burn these oxygen is required. While burning these oxygen and carbon combine together to give carbon dioxide and also combines with hydrogen to form water. The smoke that then is visible is a mixture of carbon particles, dust particles and hot gases.

To start the process or the chemical reaction of burning, a certain temperature must be reached. Once the process starts and the fuel starts burning with enough heat to burn the rest of the fuel we get a continuous fire till all the fuel is consumed.

When oxygen and the fuel molecules react in this manner, the energy that is released is the heat. Combustion can be rapid or slow. In rapid combustion, heat and light are both produced. In slow combustion only heat is produced which can be very low in amount. For example, when food is digested in our bodies oxidation takes place and heat is produced.

Radium is one of the radioactive elements which constantly emit invisible radiations. The radiations are called radioactive rays. These rays are extremely powerful and can be used in helping control such diseases as cancer because of their destructive powers.

The radio active rays are of three types  alpha, beta and gamma. Due to the emission of these rays, a radioactive element slowly disintegrates and gets converted into a different element. Radium disintegrates to finally change into lead. It takes 1622 years to convert half of it to become lead. This is called the ‘half-life’ of the radioactive element which means that it will take another 1622“ years to completely convert radium into lead.

Behind the discovery and usefulness of radium stands the genius and extreme hard work of the famous couple Madam Curie and Pierre Curie.

The phenomenon of radioactivity in uranium had been earlier discovered by Henri Becqurerl in 1896. He found that uranium emits radiations which are invisible to the human eye but are more powerful than X-rays. In 1898 the Curie couple found that thorium also emits similar radiations. They also believed that the uranium ore, pitchblende, must be having some other radioactive substance also. But to find this the ore must be refined to a much higher degree. This was not an easy task. The couple worked tirelessly day and night although they were ‘poor and could not afford a comfortable laboratory for the work. They worked in a tin-shed without paying attention to rain, storm and cold and finally succeeded in extracting 100 milligrams of radium from several tons of pitchblende.

Marie and Pierre Curie were awarded the Nobel Prize for their discovery in 1903. The unit of measure of the ‘specific activity’ of a radioactive preparation is named ‘Curie’ in their honour

 



Transparent, twinkling, beautiful - glass has been used to make decorative items such as vessels, flower-pots, jewellery, etc as well as useful items in our everyday life such as mirrors windows, furniture, bulbs of different types, containers, bottles, etc. In fact there is hardly any area where glass is not used in today’s  world.

Surprisingly the art of making glass has been known to man since ancient times. Glass beads made in 2,500 B.C. were found in Egypt. A coloured glass rod found in Babylonia is ever older. It was made in 2,600 B.C. The art of making glass must have been known to them since or even before this time.

The basic ingredients which are used in making ordinary glass are silica, sodium carbonate and calcium carbonate. All these constituents are finely powdered, mixed and then melted together in a big furnace. The melted mixture becomes homogeneous and is then cooled. Materials like silica do not crystallize but remain in an amorphous state when heated and cooled like this. The result is transparent, hard and brittle glass.

Special kinds of glass have other ingredients added to the basic mixture. Boron oxide, magnesium oxide, aluminium oxide, zinc oxide, lead oxide are some of the commonly used materials in making glasses with different special properties. To add colour to the glass oxides of chromium, copper, iron, cobalt etc are added according to the requirement.

Fibers of glass are found very useful in research and modern technology. Scientists have developed transparent glass as strong as steel. Another special glass has been produced which. changes colours when light falls on it. Glass-wool made from glass fibers is used for thermal insulation in walls, tanks, boilers, refrigerators.

 


Alfred Nobel’s name is famous because of the Nobel Prizes: the most honoured prizes in the world  in the fields of physics, chemistry, medicine, literature, peace and economics. Alfred Nobel was a Swedish Scientist and engineer. The Nobel prizes include a prize which is given to someone who has done extraordinary work to promote peace in our world. But curiously enough, Alfred Nobel was the man who invented such destructive explosives as dynamite, blasting gelatin (more powerful than dynamite), and a new kind of detonator for explosives!

Nobel was also a poet. He believed that literature and science were the most important factors in human progress. Born at Stockholm on Oct 21, 1833, he spent only two terms in school and could not attend a university, his education being taken over by tutors. To complete his education as an engineer, he was sent to the U.S.A. for one year.

Alfred Nobel, like his father, had a genius for invention. He studied explosives, especially nitroglycerin. The powerful jellylike substance which was called the “blasting gelatin” was patented by him along with the dynamite. From the manufacture of dynamite and other explosives, and from the Baku oil fields, Nobel earned immense fortune. But he was in ill-health all his life and he never married. He left most of his money in a trust which was to be used in giving prizes for outstanding work in chemistry, physics, medicine, literature, peace, ( and economics which was added in 1969). Well known organizations select the winners in each field and the Nobel Foundation of Sweden distributes the words.

Some buildings such as ancient tombs produce echo of whatever sound you make inside the building. Sometimes you can hear the same sound being echoed many times over. But if a programme of music or a lecture or a play is taking place in such a building, it will be very difficult to hear what is going on if too much echo is being produced. To avoid this cinema halls, lectures halls, auditorium are designed in_a special way so that the sounds produced can
be clearly heard by the audience.

The branch of science that studies and deals with this aspect of sound is called architectural acoustics. The fact that some materials such as plaster, reflect sound well while some others like cloth absorb sound, is taken into consideration while designing these buildings.

Echo and reverberation are the two important properties of sound. A reverberation is defined as a close group of echoes. When a sound produced inside a hall reflects back after hitting the wall we hear an echo,

When a beam of white light passes through a prism it is broken up into many different colours which form the white light. This is called the spectrum. In addition the rainbow colours, there are hundreds of parallel lines all across the spectrum. A German scientist, J. Fraunhofer first discovered and studied these lines in the sun’s spectrum and these lines are called Fraunhofer lines in his honour.

With the help of these lines, physicists and astronomers can tell amazing things - things such as what a star billions of miles away is made of, what is its temperature, how fast it is moving, and whether it is moving away from
us or towards us.

Scientists can find out these facts because each chemical element present in the universe in a gaseous or vapour state has its own pattern of line occupying a specific place in the spectrum. The lines represent the colours taken up from the light by the element when it is heated till it glows. Even if the material is very far away this rule applies. Each element leaves its ‘dark line’ (or absorption spectrum) which is different from any other element. Just as no two finger prints of two different persons can be same, no two absorption spectrum of two different elements will be same.

The positions of lines in the spectrum change with the temperature of the element, so astronomers can tell a great deal about the temperatures of stars even billions of miles away. Also, when a star is moving away from us, the lines are shifted towards the red end of the band; when it is coming towards us, the lines are shifted towards the violet end. 

The largest gold producing region on earth today is in South Africa, near the city Johannesburg. This area produces as  much as about half of the world’s supply of gold which sometimes has been over 1,000 tons.

Grasberg Gold Mine are the largest single group of gold mines in South Africa, and cover an area of 12,000 acres. The largest mine of this group has tunnels which stretch for more than 2,500 miles underground.

It was realised long ago, that the food packed and heated inside containers remained fresh for long time. But no one was able to explain the reason. When in 1860, French scientist Louis Pasteur made a discovery and said that due to the bacteria present in the food and also in the atmosphere spoil the food and make it useless and harmful to man, the working of canning was understood.

The heating kills the bacteria in the food, and the sealing of the can prevents more bacteria from getting into the food. And if well-sealed, the food inside a can should stay fresh for as long as there is no opening in the can. All cans today are vacuum-packed, which means that the air is sucked out of the can before it is sealed. This way even the bacteria in the air cannot spoil the food.

Bauxite

Aluminium is the third most plentiful element on earth, after oxygen and silicon. It  was named ‘silver from clay’ because it was found even in the ordinary garden clay. But we don’t use this source to produce pure aluminium because the refining process of it from clay are very expensive.

Nowhere in nature is aluminium found in a pure form. It is always mixed with other elements and has to be separated and purified for use. The most common aluminium source is bauxite which is aluminium oxide containing water molecules. With the help of electrical currents, pure aluminium is separated from this. This process is not very costly and bauxite is available in plenty. This makes aluminium cheaper than other metals like gold and silver. Unbelievable, as it may sound now, but true, just a hundred years ago aluminium was more precious and expensive
than even gold! It was then a new discovery and the process to separate it made it rare and expensive.