Sensor doors use motion sensors or presence sensors. The first are used to activate the door when it detects a moving object, such as a pedestrian or shopping cart. Motion sensors can distinguish between objects moving toward the door or away from it. They use microwave technology, and utilize the Doppler Effect principle. The sensors emit a high frequency microwave …

Ten, nine, eight, seven… zero – lift off. These words sound like music to an astronomer’s ears. As the countdown progresses, the rocket’s engines fire and give it the required push to tear through the atmosphere and escape the earth’s gravitation. These rockets take astronauts and artificial or man-made satellites into space. The satellites are used for communication, weather monitoring …

Pearls are some of the most beautiful gems we know, and very expensive to buy. So it may come as something of a surprise to learn that pearls start off as irritating grains of sand and other substances which get into the soft part of the oyster. The oyster is a mollusc, which means that it has a soft and …

Iridium is a precious, silver-white metal and one of the densest materials found on earth. The natural properties of iridium makes the spark plug use less voltage to create a spark, burn fuel more efficiently and spark at leaner air fuel mixtures. It delivers higher horsepower and better mileage.

All the sciences, mathematics, physics, chemistry, and biology, are playing an increasingly important role in our way of life, as the years pass and we become more dependent upon the products of science and technology. Geology, too, has a vital part to play in living today, apart from its value in furthering our understanding of the way in which our …

Most fish taste in what we would call a normal way that is, they have taste buds, the organs which detect flavours, in and around their mouths. But there are some fish, in particular those that live in very dark or muddy waters, which do not feed by sight, as they cannot see their mouth area, but also on other …

They grow from a bed of skin containing Keratin-a horn like substance. This bed lies beneath the top skin and as the nail grows it becomes hard and smooth. There is similarity between human nails and animals claws and hooves.

Clouds are formed when water evaporates from rivers, ponds, oceans, and lakes. The tiny droplets of water cling to particles like (dust, salt, or smoke). The air containing this evaporated water vapour rises and expands at higher altitudes where the air pressure is lower and clouds move with the wind. High cirrus clouds are moved by a jet stream and …

If an astronaut leaves his spacecraft during a journey, he cannot walk about in the ordinary way. There is nothing but empty space. There is not even any gravity to pull him in one particular direction. He can only guide himself by the same means as the spacecraft itself – by rocket propulsion. So when astronauts do leave their spacecraft …

On contact with an allergent, chemical substances are released from mast cells and basophils. The chemical mediators (e.g. histamines) in turn attach themselves on to H-1 receptors to produce allergic effects. Anti-allergen drugs block these chemical mediators. The drugs also produce down regulation of H-1 receptors.