Questionnaire?????

• How is the age of the earth calculated?

The concept of radioactivity, according to which atoms of certain heavier elements like uranium and its salts have the power of emitting some penetrating radiations spontaneously and gradually change into atoms of stable elements, is an excellent tool which can throw light on the age of rocks or the earth. If a radioactive isotope and its decay products remain trapped in a rock, the measurement of the portion of the parent isotope that has decayed enables the age of the rocks to be determined. For example, in uranium bearing rocks, U238 reached equilibrium with its decay products in about 2 million years. After this time, the net result of the disintegration process is the production of Pb206 from U238, while the intermediate products remain in constant concentration. The measurement of the ratio of Pb206 to U238 enables the age of the rocks or the earth to be established. The measurement of the oldest rocks have established that age of the earth must be about 4,500 million years.

• How is an American diamond different from ordinary diamond?

Synthetic diamonds are called American diamonds. Although now they are manufactured by various countries. Synthetic diamonds are man-made diamonds and they differ from naturally found one in shape, size and impurities. Synthetic diamonds are produced by putting fraphite to very high pressure (10,000 atmospheric) and very high temperatures (above 3,000 degree Celsius). Du Pont, De Beers, GE(General Electric) are some of the companies producing synthetic diamonds for commercial purpose.

• What is reservoir-induced seismicity?

The filling of lake water in a dam site and its pressing down the ground with its load, generating new stresses underground is responsible for reservoir-induced seismicity(RIS). It is noticed that the stresses build up to the peak slowly over several years after the initiation of the filling and then there is a sudden failure of ground, releasing these stresses in the form of earthquake. The earthquake that occurred in the Koyna dam site, near Shivaji Sagar lake in Maharashtra in 1967 as an example of this. RIS depends on
(a) Rate of increase of water level,
(b) Duration of high water level maintained,
(c) Maximum height attained,
(d) Deeper infiltration of the impounded water through passage provided by faults, joints, fractures, shear zones and cavities,
(e) Existence of deeper tectonic conditions such as stresses build up in pre-existing fault planes and wark zones,
(f) Brittleness of the rocks such as quartisites, granites, basalts etc. Only if all the last time conditions are present would there be an earthquake.

• Why are T-shirts and bush shirts called so?

Col Bush, a British Army Officer attached to the Indian Army in the early 1930's invented this kind of coat-cum-shirt for wear during the summer. It became very popular and came to be known as bush shirt. Originally it had four pockets, a belt and shoulder straps. T-shirt is so called because when it is spread out, it looks like the English letter 'T'.

• How is jogging different from running?

Jogging implies running at a slow, steady and gentle pace, especially on regular basis as form of physical exercise. The word 'jog' originated in the 14th century. It is probably a variant of dialect 'shog' meaning to shake. Running implies going faster than walk, espeacially going steadily by springing steps so that both feet leave the ground for an instant in each step. The word 'run' is derived from Old English 'rinnan'.

• What does devil's advocate mean?

Origin of the term 'devil's advocate' lies in the tradition of the Roman Catholic Church wherein a person appointed to challenge a proposed beatification, canonisation, etc., is known as devil's advocate. Beatification is an act by which a dead person is formally declared as blesses while canonisation is the process through which one may be declared as saint in Christian tradition.

• Why is acid test called so?

An acid test is a rigorous or decisive test of worth or quality. It is so called due to the fact that in earlier days, gold was dipped in Nitric Acid, whenever there was any doubt about its purity. Nitric Acid damages every metal except pure gold ( hence the latter is called the noble metal).