Category Applied Science & Technology

What is the principle of an autopilot?

Most large planes have an autopilot. This is a device operated by a computer. It will fly the plate without the pilot’s touching the controls. These autopilots can even control take offs and landings.

 

 

 

 

 

 

 

The principle of an automatic pilot is similar to the automatic steering of ships, but here three gyroscopic sensors and their associated equipment are used to control the three variables in aircraft position.

These three variables are yaw, pitch and roll. The complex autopilot system uses an airborne computer which activates servomotors for introducing necessary corrections. A radio or radar link to the computer allows control from the ground for automatic takeoffs and landings.

 

What is bar code?

A bar code is computerized information encoded in a pattern of black and white stripes. The black and white lines represent IS and OS and can be read by light. They carry encoded information – from the membership number of a sports club to the price and stock number of a packet of washing powder in a supermarket. In fact bar codes are used to store data of all kinds.

The code is scanned by a beam of light. When a beam of light is passed over the bar code only the white stripes reflect back the light. This is picked up by a photo – detector which produces a pulse of electricity when it receives light. So the black and white bar code is translated into on/off pulses of electricity. These pulses are fed into a computer for decoding. Nowadays laser beams are being used for reading the bar codes.

What is LPG?

         The term LPG stands for liquefied petroleum gas. LPG is commonly used for domestic cooking purposes. It is supplied in gas cylinders that need to be replaced when their fuel contents are consumed. The supply in gas cylinders contains a mixture of liquefied butane and iso-butane under pressure. The mixture remains a liquid under pressure but the highly volatile liquid fuel in the cylinder evaporates when pressure is released. The gaseous mixture starts going into the burner of attached stove or oven. Here it is ignited and the blue flame is used for different purposes.

         LPG is used as a cooking fuel. This is also used in water heaters, space heaters and furnaces. This gas is also used to heat incubators and brooders, to sterilize milking utensils and other equipments, dry fruits and vegetables and prevent frost damage.

         Moreover, LPG is highly combustible and forms an explosive mixture with air, therefore, any leakage followed by its mixing with air can cause a severe explosion just by the ignition of one match stick. In order to make gas leakage easily detectable some strong smelling substance is added to LPG. Before igniting the match stick we should be sure that there is no such smell near the gas cylinder or in the kitchen.

 

What is Plastic Surgery?

              Plastic surgery is a branch of surgery devoted to restoration, repair and correction of malformations of tissues. It concerns not only return to normal appearance but also the restoration of function. The field of plastic surgery has several sub-divisions such as cosmetic surgery, management of congenital defects, burns, wounds and other acquired defects.

             Cosmetic surgery deals with improving the appearance of tissues or organs such as the nose, face, eyes or breasts. The most common types of cosmetic surgery are face lift to remove wrinkles from the face and neck and a rhinoplasty to change the shape of the nose.

             Plastic surgeons treat physical defects that exist since birth (congenital defects) or are caused by injury or disease. Often the body part that is defective or damaged does not work as it should. In such cases, the surgeon does reconstructive plastic surgery. This often requires grafting. In grafting skin muscle, bone or cartilage is transplanted from a healthy part of the body to the hurt or damaged part. Sometimes reconstructive surgery involves reattaching several limbs, rebuilding damaged tissues, restoring damaged blood vessels and nerves. Plastic surgeons are available almost in all the hospitals.

             Plastic surgery has been practiced for hundreds of years in China and India. Chinese and Indian doctors were reshaping noses and lips long ago.

 

What are different types of telescopes?

            A telescope is an optical instrument used to see distant objects clearly and magnified. The telescope was invented in 1608 by a Dutch optician Hans Lippershey. In 1609, the Italian astronomer Galileo made his first telescope and observed the rings of Saturn and Jupiter’s moons. Today there are three main kinds of telescopes: refracting telescopes, reflecting telescopes and radio telescopes.

Refracting Telescopes: A refracting telescope makes use of two lenses fitted at the end of a tube. An astronomical telescope consists of one larger size convex objective lens and a convex eyepiece while a Galilean telescope makes use of a convex objective lens and a concave eyepiece. Modern refracting telescopes usually contain complicated lens systems to correct chromatic aberrations.

Reflecting Telescope: A reflecting telescope is made of a concave mirror that gathers and focuses light waves. Another mirror near the point where waves come together reflects light into the eyepiece.

            A Newtonian telescope uses a mirror set at a 45° angle to reflect the light into the eyepiece. A Casegranian telescope has convex mirror which reflects light through a tiny hole in the centre of the objective mirror. The light passes through to the eyepiece, which makes the image larger.

           The largest reflecting telescope in the world is at the Yerkes observatory in Wisconsin. Its objective lens has a 102cm diameter. The Palomar observatory in California has a reflecting mirror with a diameter of 508cm.

Radio Telescopes: A radio telescope has a huge reflector shaped like a bowl which reflects radio waves to a detector. Radio telescopes are used in astronomy. These telescopes can be used under all weather conditions.

What is Plastic?

            Plastics do not occur naturally but are manufactured. The word ‘plastic’ has originated from the Greek word ‘Plastikos’ which means ‘to mould’. It is made from simple organic chemicals. It has many varieties and colours.

            Plastic was invented by Alexander Parkes of England in 1862. In those days it was called ‘Parkesine’ after him. Parkesine was the first plastic ever produced.

            Many plastics have ‘poly’ in their names for example, polythene. Poly comes from a Greek word meaning ‘many’. Polythene means ‘many molecules of ethene joined together’.

                   The manufacturing of plastic on a commercial scale was started for the first time by Leo Hendirk Backeland. He made it from phenol and formaldehyde. Subsequently, new techniques were developed for the production of plastics. Today, scientists have discovered many raw materials which are used in the making of various kinds of plastic products. Most plastics are made from chemicals found in oil, although a few come from wood, coal and natural gas. Common types include polythene, polystyrene, PVC and nylon.

                  Today, plastic has become an integral part of our life. Its uses are endless. Transparent plastics are used for making lenses and windows of aeroplanes. Polythene bags, a plastic product, are used in almost all walks of life. Articles of domestic use like buckets, cups, brushes, combs, baskets, cabinets for radios, transistors etc. are also made of plastics. Toys and sports goods made from plastic have flooded the markets everywhere. The yarn for making Terylene cloth is, in fact, made from plastic. Today scientists have even succeeded in developing heat insulating plastics. Foam cushions, seats in trains, cars and aeroplanes – all are made from plastics. Now, plastics are used as surgical aids also. There is hardly any field of life in which plastics are not used.