54 items in this section. Displaying page 2 of 6
Why does Milk spill over when it Boils?
How many times have you seen milk boil and spill over, and wondered why this happens? To answer this question we have to know a little more about the composition of milk. Milk and its composition Unlike water, milk is not a simple liquid. It is a colloid and contains many substances in suspended form. These substances are mainly protein, sugar and fat. When milk is heated slowly, the proteins and fat get separated. Since they are lighter than the milk they collect on the surface in the form of a layer called cream....
A Fish with Three Hearts: Cuttlefish
It is said to be a royal among sea animals because it has blue blood, literally. And the cuttlefish has a large heart. Actually, it is not one but three hearts. And it is not even a fish but belongs to the same family as the squid and the octopus. They are called the cephalopods, which literally translated means head-foot. The blood of the cuttlefish is blue because of the huge amount of copper in it....
How does a Submarine Work?
Jules Verne in his science fiction, 20,000 Leagues under the Sea, mentions a ship, Nautilus, which could dive beneath the waves and surface again when it wanted to. Even before submarines were thought about, Verne had created the blueprint of this technological marvel. Not only did he describe the machine, but he also explained, in great detail, how it worked. In fact, today’s submarines use exactly the same technology as Verne’s Nautilus did! How does a Submarine Work?...
What is a Volcano?
What is nature’s most powerful, most destructive, most dangerous form? Some would say an earthquake, others a cyclone. However, these phenomenon are relatively smaller and less destructive in scale compared to the fury of a volcano. Fourteen miles southeast of Naples in Italy, lie the remains of an ancient town called Pompeii. The city flourished under the shadows of the towering Mount Vesuvius. In 79 AD, the volcano erupted, destroying the cities of Pompeii, Herculaneum, Stabiae and Torre Annunziata....
Why do Humans Sweat?
It is an annual ritual in most Indian homes. With the onset of summer it is time to bring the rusty, rickety old coolers down from the terrace and get them repaired. The reason is obvious – it is difficult to live through the hot, sweaty Indian summer without an air cooler. But did you know that the human body has its own cooler as well? Think of the times you have travelled in a car....
How Does Satellite TV Work?
Nine ‘o’ clock. It’s time for your favourite serial on television. Have you ever wondered how the same serial can be viewed by millions of people across the world? This is possible because of satellite television technology. It uses man-made or artificial satellites to send your favourite serial to your television set. But why do we need satellites for this purpose? How Does Satellite TV Work? The earth is round To understand this, we have to first take a look at the shape of our earth....
What is the Weight of Air?
As you stand in the middle of a playground or while you are sitting in your class, there is an immense weight right over your head, but you do not feel it! This is the weight of the atmosphere, or air, as we know it. Composed of nitrogen, oxygen, carbon dioxide and other gases, it surrounds the earth like an envelope. And, it extends almost a thousand kilometres above the Earth’s surface. Like all other substances, air also has weight....
An Organism that is visible from Space
The elephant is the largest land animal. The Blue whale is the largest sea animal. But however big these animals may be, they can not size up to the colonies built by tiny little sea creatures – the coral. The colonies built by corals are called coral reefs. Coral reefs can be as huge as big islands or even as big as a country! These reef-building corals are not single animals. A coral is a colony made up of many individual animals called polyps....
How do Earthquakes Happen?
Simply put, the shaking of the earth caused by a sudden shifting of rocks below its surface, is called an earthquake. The earths crust or outermost layer, is not made of one single piece of solid rock. It is actually made up of independent sheets of rocks called tectonic plates. The tectonic plates of the world were mapped in the second half of the 20th century. These plates slide against each other, giving rise to physical changes in the earths topography....
What is the Ozone Hole?
On beaches as well as on the cricket ground, it is always possible to spot people with some kind of cream on their bodies or faces. Remember the South African pace bowler Alan Donald or ‘White Lightning’ as he is called, with “war-paint” on his face? No, it is not an attempt at camouflage, simply an effort to gain protection from the ultraviolet rays of the sun. And therein lies a paradox – it is the light and heat of the sun that sustains life on earth, but among its many friendly rays are some harmful ones as well....