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Tuesday, 19 March 2013
Saturday, 16 March 2013
When were the world fairs started?
We do not have definite information about the beginning of the fairs. But in ancient times when there were no means of communication and man had to go long distances in search of articles of daily needs, the traders used to assemble on a fixed day at a fixed place to sell articles of daily use. People used to purchase articles of their needs in exchange for animal hides or grains.With the advancement in the modes of communication, the commercial...
Do giants live on earth?
In many parts of Europe and Asia, there are legends of the existence of giants in ancient times. We also read many stories in magazines and newspapers about demons and giants. After reading these stories, one feels that giants exist in some parts of the world. Since many races of pygmies are found on earth, it is logical to think that there may be races of giants on the earth as well. In fact, giants have existed in myths and story books only. There...
What causes an echo?
When we speak loudly in a big empty hall or in a temple, we hear our own sound repeatedly. This is called echo. An echo can also be heard by shouting near a deep ditch or a well. The thunder of clouds, is another example of echo.We know that sound travels from one place to another in the form of waves. The velocity of sound in the air is (340 metres 1100 ft) per second. When we speak, the sound waves emanating from our mouth spread out in all the...
Friday, 15 March 2013
Where have Seven Wonders of the world gone?
We have often heard about the seven great wonders of the world. Would you like to know what are these seven wonders? They are: The Pyramids of Egypt, The Hanging Gardens of Babylon, The Tomb of Mousolus, The Temple of Diana, the Colossus of Rhodes of Helios,The Statue of God Zeus and The light House of Pharos near Alexandria. Out of these seven wonders, the Pyramids of Egypt are preserved only. The story behind their construction is very interesting.The...
How was the calendar started?
In the beginning of the civilisation, when man observed the sun rising and setting, he felt the occurrence of the day and night. The idea of the month came with the observation of the phases of the moon. And probably the change in the seasons gave birth to the idea of the year. Finally with the development of science, man came to know things more correctly. He defined the period of one revolution of the earth round the sun as one year. The time taken...
How was the needle invented?
Needle is a tiny thing, but is really very useful. Had there been no needle, we would never have got our clothes stitched. It has been serving the mankind for thepast thousands of years. The excellently stitched clothes you see today speak of the marvel of the needle. Not only this, millions of people earn their livelihood in the world with the help of the needle.We do not have definite information regarding the invention of the needle. But this...
How was the circulation of currency started?
Generally the word currency denotes conins and paper notes issued by a government for buying an article. Today currency forms the basis of all the trade in the world.In the beginning of the civilisation, whenever somebody wanted to buy anything, he would barter it with food grains, tobacco, hides, salt etc. In villages and under-developed countries this system is still prevailing. It is known as barter economy. Such a system used to cause lot of...
Why is the census taken?
Census operation is now common in almost all the countries of the world. Nothing can be definitely said as to how and when it was started. But it seems that man realised the importance of census when he started living in larger groups. It is said that the population of the world was 85 million in the year 4000 B.C. It is evident from this fact that the system of census was very much developed at that time also. After all, why is the census taken?...
How are the pearls formed?
Pure pearls are very precious. You will be surprised to know that these are made by a small sea-creature, oyster. This can crawl on the ground also. The biggest tragedy with this little creature is that fish of the sea or the bigger members of its own family eat it away. When the oyster comes to the sea shore to save its life man eats it. In order to protect itself, it forms a hard shell around its own body. Pearls are made within this hard cover....
What is rubber?
The history of rubber is as old as that of nature. Rubber is obtained from special type of plants. Three million years old fossils of the rubber producing plants have been found. It is a highly elastic organic material. It can be stretched eight times to its original length. A while liquid called latex comes out of the trees from which the rubber is made. When this liquid is dried up we get rubber. Rubber so obtained is called natural rubber. In...
How the postal system started?
We are all familiar with the importance of the postal system. It is because of this that we are able to receive letters written by our friends and relatives from England or America in six to seven days. Similarly it takes only 2-3 days for the letters to reach us from Bombay, Calcutta or some other places. All this is the marvel of the postal system. Mail vans, trains and Aeroplanes carry letters sent by us. Millions of people are engaged in this...
What is malaria and how it spreads?
All of us are familiar with malaria. More than two million people of the world die of this disease every year. This disease is found in all the countries of the world, but is more common in Central and South America, Far East Asia, Central Africa, countries around the Mediterranean Sea, hot belt areas and places situated on the seashores. Previously it was believed tht malaria is caused by a poisonous gas produced in dark and damp places. The word...
How do we get wool from the sheep?
We wear warm clothes during the winter. These clothes are made of wool. We get wool from the sheep. Hair grow on the body of the sheep as they do on our head. This hair of the sheep is called wool. The wool protects the sheep from cold in winter. Do you know how wool is obtained from the sheep?The hair of a sheep are cut once in a year. When the winter is about to end and the summer is round the corner, the sheep does not require hair. At that time...
How is copper useful to us?
After gold, copper was the first metal to be discovered by man. History reveals that it was used by the man in stone age. It is found in nature in solid or granule form and it is possible that it was discovered in this state only. Man had started using copper instruments, weapons and ornaments around 6000 B.C By 4000 B.C. the mining of copper had begun. For thousands of years copper was the only metal used by him. Later, when he came to know...
What is helium gas?
Most of the gases can be prepared in the laboratory but there are some gases which are found in nature only. Helium is one of them. It is an inert gas. It is odourless and tasteless. Helium has some special characteristics due to which it has proved very useful for us. Next to hydrogen it is the second lightest gas but it has a speciality that unlike hydrogen it is not inflammable. On account of its lightness and non-inflammability, it is used in...
Wednesday, 13 March 2013
How is oxygen useful to us?
Without oxygen there would have been no life on this earth. Without it no living being-trees, plants or animals-can survive. Hence it will not be a misnomer to call it a life-giver. Do you know what it is and why it is absolutely essential for us?Oxygen is a gaseous element. This was first discovered by Lavoisier and Priestley. It is a colourless, tasteless and odourless gas. In the atmosphere the air contains 21% oxygen, 78% nitrogen and rest one...
How is liquid converted into vapour?
It is commonly observed during the rainy season that water falling on roads and streets disappears after few hours. Similarly, in summer, wet clothes dry up very soon. Do you know where this water goes? This water gets converted into vapour. Conversion of water into vapour is called evaporation.How does evaporation take place? Every substance is made up of very small particles called molecules. These molecules are held together by strong forces of...
How is silicon useful to us?
Silicon is a non-metallic element. It is not found in nature in a pure form. Pure silicon is a hard, deep black or brown coloured material. It shines like metals, and is crystalline in nature. At Ordinary temperature it does not react with other elements, but at higher temperature it makes compounds with other elements. The earth's crust has 28% silicon whereas china clay contains 50% silicon. It is also found in rocks, sands, water, bones, etc....
Why do hot things burn us?
An object is said to be hot if its temperature is more than our body temperature. If we touch such an object, heat flows from it to our body and we feel its sensation. Similarly, an object is said to be cold if its temperature is lower than our body temperature. When we touch it, heat flows from our body into that object. Do you know why it happens like that?We know that our body is made up of cells. And consequently these cells are made up of molecules....
How is dew formed?
In the early hours of morning you might have seen small drops of water on grass, plants and trees shining like pearls in the sun's rays. These water-drops are called dew. Quite often people think that dew drops, like rain water, fall on the earth from sky during night but this is not true.Dew drops are formed due to condensation of water vapours. Air around us contains water vapours which we call moisture or humidity. Hot air contains more moisture...
When were newspapers started?
Newspaper is the most effective medium of communication in the mordern world today. Millions of newspapers are published in the world. Do you know when newspapers were started and how much effort did it take to bring them to the present form?According to recorded facts, the first newspaper of the world was published in China around 1000 years ago. Its name was 'Tching Pao' which meant 'news of the capital'. The government used to communicate main...
What is quicksand?
Quicksand is a peculiar creation of nature. Though it has an ordinary appearance, yet it is very dangerous. From a distance, you cannot distinguish between ordinary soil and quicksand. By mistake, however, if some body enters quicksand, he will slowly go down and finally sink in it. Once you are trapped in quicksand, it is very difficult to get out of it. Quicksand can devour anything big or small. Do you know what quicksand is, how it is formed...
Tuesday, 12 March 2013
Monday, 11 March 2013
When were the advertisements started?
Advertisement have become a part of our lives. Thousands of goods are advertised through the media like radio, television and the press. They help to popularise the products among the consumers and buyers and give a boost to sales.Today, in all the countries of the world, there are advertising agencies which advertise goods in many attractive ways. Besides increasing the sale of goods, advertisements are also used to make the public vigilant. Moreover,...
What is Nobel Prize?
Nobel prizes are awarded every year and the winners of this prize are talked about throughout the world. Their life-sketch and works are published in the newspapers. Their names are heard on radio and television. After all what is a Nobel prize and why it is given so much importance?Under this prize, the prize-winner gets a gold medal, a certificate and a large sum of money. The Nobel prize is the world's most important prize. This prize is given...
Why was the Great Wall of China built?
We all have heard the name of the Great Wall of China. this is the longest wall of the world, being more than 2694.4 kilometers (1684 miles) long. Its height ranges from 4.57 to 9.2 meters (15 to 30 feet)while thickness is 9.75 meters (32 feet). The costruction of this great wall was started in the year 221 B.C. and it took almost 15 years to complete this work. This was built of stones and bricks. Now the question arises: what was the necessity...
What is the Red Cross and how was it born?
The Red Cross is an international humanitarian organisation.Initially its field of activity was confined to looking after soldiers wounded in wars.But now it works for alleviation of all forms of human suffering.Almost all the countries of the worlds branches of Red Cross which works both during war and peace.It serves helpless people without any discrimination on grounds of caste,creed or nationality.During peace time,its activities are:to give...
Why do watches have jewels?
Whenever somebody purchases a watch he often enquiries about the number of jewels in it. The number of jewels is inscribed or printed on the outer cases or the dial of the watch. It is commonly believed that the larger the number of jewels, the better and more durable the watch will be.Would you like to know what are jewels and why are they fitted into watches?A good watch is one which gives correct time and does not easily go out of order. If you...
Why does the rising and the setting sun appear red?
When the sun rises in the morning, it appears like a red ball. As the day advances, the colour appears white, but at the time of sunset in the evening, the colour again appears red. Do you know why it is so?We know that the earth revolves round the sun. The part of the earth receiving the sunlight is lighted and we say it is day in that part. We also know that the white sunlight comprises seven colours-violet, indigo, bleu, green, yellow, orange...
How did America get its name?
Today America is regarded as the most affluent and powerful country of the world. Its development is mainly a story of last two hundred years. Earlier it was divided into 13 small colonies. We know that America was discovered by Columbus. Then why was it not named after him?It is a matter of chance. The story as to how America was named is very interesting.The world famous Italian traveller Columbus, set out on a sea voyage in search of India. He...
Saturday, 9 March 2013
Are the molecules of all substances in motion?
Every substance is made up of very tiny particles called molecules. A molecule is the smallest part of the matter that can exist independently and exhibits all the properties of that matter. For example, if we take a molecule of sugar, it will exhibit all the properties of sugar such as taste, shape, colour etc.Molecules of different substances differ in size. Some are only few billionths of a centimeter in size while some other molecules are thousands...
Why is gold so costly?
From ancient times, gold has symbolised affluence. The statues and temples of our gods and goddesses are decorated with gold ornaments. Kings and emperors always gave great importance to gold. Man has always shown a great affinity for gold. After all what is so special about gold that it has always been costly and day by day it is becoming costlier?The preciousness of a substance depends on many factors. First of all it is its rarity. Secondly, the...
What causes baldness in people?
There are many theories regarding baldness. Some people treat baldness as the indication of arrival of old age while some are of the view that bald men are intelligent. Baldness is also treated as a sign of richness. Some people think that bald men are fools. Whatever may be the significance of baldness, one thing is certain that by losing hair, man is deprived of that beauty which otherwise he would have.Baldness or alopecia is mainly of two types:...
How is dust useful to us?
Most of the people think that dust is very harmful to us. But this is not true. Dust also is very useful to us.Before we go through the uses of dust, it is essential to know as to what dust is and how it is formed?Every solid substance is composed of very small particles.When these small particles of matter are scattered, they become dust particles. For example, if we go on breaking a brick or a stone into small pieces, they will turn into small...
How do we remember things?
The processes of learning, memory and understanding are directly related to behaviour. Almostall human behaviour is learned. Learning takes place all the time. The brain keeps a trace of all the events taking place in our life.According to psychologists there are four kinds of learning. Classical conditioning is the simplest kind of learning. Ivan Pavlov studied it during early 1900s. He offered a dog food and at the same time rang a bell. The sight...
