Saturday, March 18, 2006

Lightning Arrestors

Benjamin Fraklin was fond of kite flying. One day he was flying a kite made of silk cloth mounted to a wooden cross and fastened using a steel wire. The tail of the kite was connected to a long metal string at the center. The end of the string was connected to a silk ribbon which he held in his hand. He was enjoying his kite flying and suddenly a thunderstom broke out. A severe lightening flashed across the dense clouds. Suddenly Benjamin Franklin experienced severe shock in his hands and noticed there were sparks from the metal string. He panicked and left the kite, Soon he saw the ribbon in flames.

He realised that the dark clouds were laden with electrical chargeand the subsequent lightning produced heavy electric currentwhich passed through the metal string causing sparks. fortunately for him the silk ribbon he was holding was abad conductor of electricity and he dropped the kite well in time. He also realised that when ever lightening occurs, the electric current produced has the tendency to pass down to the earth through some medium. This gave birth to the invention of the lightning arrestors that are installed in tall buildings.

He thought that if a conducting medium is installed in tall buildings, it would attact the lightning current and pass it to the ground without afecting the building. All the modern day arrestors make use of the same principle.

What is solar enrgy?

If any form of energy is available in abundance in India its solar energy. Now the concept of solar power plants is slowly catching up. The steam generated from the large sized solar heaterscan be used to actuate a steam turbine which generates electric power through generator. Recently the tourist island of Bangaram, in Laskshadweep Islands, has acquired a solar power plant. Hitherto, it had to depend solely on diesel power plants, for which diesel was being transported from the mainland at a high cost. The Bangalore based electronic division of BHEL unit had earlier installed a solar power plant of 10kw capacity. This wass upgraded recently to 50kw hybrid solar pwer plant to ensure full power supply needed for the island. BHEL has installed 8 such power plants till date.

Thursday, March 09, 2006

Moon and the Gravitational force

Have you ever wondered how the moon is able to hand in the sky like a giant balloon and why it is not pulled down by the gravitational force of the earth? After all, the earth has a powerful gravitational force sufficient to pull the moon downwards towards it. Considering the fact that the gravity on the moon is only one-sixth of that of the earth, it should have come crashing towards the earth long ago. Why then has this not happened? Isn't the earth pulling the moon with all its might towards it. In which case how does the moon resist it?

Though the moon appears to be stationery, it is, in fact, revolving round the earth in a steady orbit. As per Newton's law, every revolving object gives rise to a centrifugal force which tends to push the object radially outward from the centre of the revolution. The moon is revolving at a specific speed which creates a centrifugal force exactly equal and opposite to the pull of the earth. Thus the forces are balanced and the moon neither tens to move away from the earth, nor towards it. You might then wonder why the moon appears to be motionless! Objects closer to us appear to move more swiftly than when they are away from us. For instance, an aircraft while taking off seems to move very fast in the runway, but when it flies high in a clear sky, it appears to move slowly. So, it is no wonder the moon, which is 384400 km away from us, appears to be motionless, though it is revolving around us at a high speed.

Wednesday, March 08, 2006

What are Anagrams

Alexander Graham Bell, who invented the telephone, was also a writer. Wanting to make sure that his writings would not be appreciated solely because he was famous, he chose an alias HA Largelamb by mixing the alphabets of his name, A Graham Bell (This is called creating an anagram)

King louis XII of France was so fond of anagrams that he appointed Thomas Billon as the royal anagramatist. His full time job was to convert the names of the court nobles into funny anagrams, to amuse the king.

The Smallest Country

The Vatican is the smallest country in the world. It is an independent sovereign state within the bondaries of Rome, the capital of Italy. It became an independent state only after 1929. Right from inception, it has been the spiritual and administrative centre of the Roman Catholic Church. The city state has a daily newspaper, a railway station, and its own bank. It has an area of just 0.5 sq. km and a population of little over a thousand, though it attracts millions of visitors every year. The main attractions in the Vatican are the Michaelandgelo Frescoes in the Sistin Chapel and the imposing facade of St. Peter.