Science & Mathematics Questions & Answers

Quartz is used in watches as it acts as a piezoelectric oscillator. As a potential difference is applied across quartz, stress is generated across the perpendicular faces of the quartz crystal. It is known as reverse piezoelectric effect. The word piezo in Greek means pressure and, therefore, piezoelectricity means pressure electricity. It takes place in some crystals like quartz which …

Prince Henry was the fifth son of King John I of Portugal and of Queen Philippa, grand-daughter of Edward III of England. In his youth he had proved himself to be a brave warrior, but his one desire in life was to extend the sea-routes of the world and to make his country rich by trade. He set up an …

Pig iron is the intermediate product of smelting steel ore with coke and resin. Pig iron has a high carbon content, typically 3.5-4.5%, which makes it brittle and not useful directly as a material except for limited applications. The traditional shape of moulds used for these ingots was a branching structure formed in sand, with many individual ingots at right …

Mercury can claim the title for the “weirdest” planet in the solar system, apart from being the smallest and the innermost. It has the wildest temperature extremes – from 800’c to to 300’c and drifts from being the nearest to being the farthest from the sun. Reaching mercury poses significant challenges as the planet orbits close to the sun. Hence, …

Liquid ammonia acts as a refrigerant in ice plants. Evaporation of a liquid needs heat energy. When liquid ammonia vapourizes, it absorbs large quantities of heat without changing its temperature. For these reasons, ammonia is widely used as a refrigerant. About 17 g of liquid ammonia absorbs 5,700 calories of heat from the surrounding water. This cools the water and …

It is harder to walk uphill than downhill because you must lift the weight of your body and to do this requires greater energy than that needed for walking on the level. To create this greater energy your muscles require to give extra lift, your heart has more work to do to feed the blood cells and remove their waste …

High altitudes normally begin at 1500 metres above sea level. At such altitudes, the atmospheric pressure is considerably lower than at sea level. To give some examples: the pressure at sea level is 14.7 pounds per square inch and it decreases through 4.3 psi at 30,000 ft to 1.6 psi at 50,000 ft. Because of this, the air expands as …

Long ago, the best hats and headdresses in Europe were made in Milan, Italy. A citizen of Milan was called Milaner, and although the spelling of the word has changed, a hat maker is still called a milliner, wherever he or she lives, and the hats the milliner makes are called millinery.

These interactions depend on the nature of the light and the nature of the material. For instance, light falling on a leaf encounters many pigment molecules, predominantly chlorophyll. These molecules absorb light from the red and blue ends of the visible spectrum. The remaining light is scattered back because molecules in a leaf are tightly packed and so, we see …

Ordinary glass is soda-lime glass and is a mixture of silicates of sodium, potassium, calcium and aluminium etc. It is brittle because its molecular structure is composed of tetrahedral crystals. These crystals do not have a good large-area orderly crystalline structure. Therefore, when it is under stress, the structure gets ruptured.