The wind tunnel is a device that is used to study the way an object behaves when the air flows over it. There are powerful engines that generate a constant flow of air throught the tunnel. The object is attached with sensors that show whether the airflow is smooth or turbulent and also measure the forces such as lift and friction generated by the air flow.
The tunnels are largely used by aircraft manufactures to test new modles of aircrafts. Architects test models of bridges and buildings to make sure that they are powerful enough to withstand high winds.
How is the waste disposed off?
Waste disposal refers to various methods that people use to get rid of rubbish things that are no longer needed. The ever-growing human population is creating problems for the environment. The human waste or sewage needs treatment to make it harmeless.
Untreated sewage, when disposed off into the sea leads to overloading of the natural processes of decay which can spread disease or cause rapid growth of harmful algae.
Waste from our home like containers, bottles and can be recycled.
Much of the waste is buried underground and the site is then used for construction. Some waste is burned in incinerators. The factories, espacially chemical factories, have to treat their waste before releasing them into rivers or in the air.
What is a Visual Display Unit?
A Visual display unit or VDU is a part of a computer. It shows visual information, such as text and computer graphics on a screen. The most common type of VDU is the cathode ray tube or CRT.
A CRT works like a television screen. It builds up the picture from hundreds of lines of glowing phosphor dots. Other CRTs use glowing neon gas, liquid crystals and glowing phosphorous to form images.
How does an ultrasound machine work?
Ultra sound machines are used to check the progress of unborn babies, still in the mother's womb. This is a painless process for mother and is harmless for the baby. Ultrasound is a sound that cannot be heard, Because its frequency is greater than the highest frequency that the human ear can hear. It is used to reveal details that cannot be normally seen.
The ultra sound machine scanner transmits ultra sound into the mother's body and recives reflections from inside. The reflections are displayed as a picture on a screen.
How is Soap made?
Soap is used to clean ourselves of dirt and grease. It is a compound of a metal, such as sodium or potassium and an inorganic acid called fatty acid. It is made by heating fat or vegitable oil with a strong alkali like caustic soda.
Salt is then added to the mixture to make the soap come out of solution and glycerine is left as a useful by-product. The soap is then shaped into bar and sometimes perfumes are also added to it.
What is a pyrex glass?
Pyrex is a type of glass which is resistant to heat. It is made by replacing some of the silica in normal glass with boron trioxide, Also known as borosilicate glass (Borosil being a brand name),
Pyrex expands very little, when it is heated and and this pervents it from cracking.
It has a higher melting point than normal glass and is resistant to many chemicals. Pyrex is used in laboratories and at homes in ovens. It is also used in making astronomical telescopes.
How does a photocopy machine work?
A photocopy machine is used to produce copies of documents. The machine has a drum-shaped metal plate which is given a charge of static electricity. The plate is coated so that that it conducts electricty when a light shines on it.
The document to be copied is placed on a sheet of glass. A bright image of the document is focussed onto the charged plate. Where light strikes the plate, the electric charge flows away.
The plate, therefore carries an image of the orginal document in the form of a pattern of static electricity. A black powered pigment called torner is sprayed all over the plates.
It sticks to the charged areas only. A sheet of paper is pressed against the charged plate. The toning powder sticks to the paper and the image is madde permanent by heat.
Where do we get petroleum from?
Petroleum is also known as crude or mineral oil. It is a thick, dark liquid used to make a wide range of liquid used to make a wide range of liquid and gas fuels. It is a fossil fuel made millions of years ago from small secaying plants and animals that lived in the sea . Oil is searched in rocks also where it is often found.
On finding the exact location of oil deposits, test wells are drilled to discover how big the oil field is. Finally, the well itself is drilled to allow the oil to be pumped out.
After extracting crude oil, it is processed or refined. The world's richest oil reserves are in the USA, the Middle East and the russian countries.
What are petrochemicals?
When petroleum or crude oil is refined by a process called cracking or fractional distillation, it gets separated into some valuable chemicals called petrochemicals.
The petrochemicals include propanone and ethene. Propanone is used in the manufacture of syntheic fibres including rayon. Ethene is used to make ethanol and polythene.
Ethanol is the alcohol in the alcoholic drinks and is used to produce many other chemicals. It is also used as a fuel. Polythene is used as pacaging matrial. Ethene is used as an artificial fruit ripner. Some gases like methane, ethane,propane and butane are also produced.
How is the milk pasteurised?
Pasteurisation is the process of killing disease producing micro-organisms in food items by heat. A common use of Pasteurisation is the heat treatment of milk. Special equipments heat the milk to 62 o celcius for 30 minutes or 72 o celcius for 15seconds.
This kills off dangerous bacteria, which could cause diseases turberculosis and other bacteria which could turn the milk sour.
Higher temperatures are used to increase the shelf life of milk, Which does not get sour for days. This type of milk has to be heated to 130-150 o celcius.
The treatment of milk by this process has reduced the levels of diseases causing diarrhoea and sickness.
What are Optical Fibers?
Optical Fibres are fine strands of glass. The Fibers have a core of pure glass surrounded by a different kind of glass called cladding. The cladding bends any light rays that strike it back into the centre of the fibres.
Optical Fibres are used in telecommunication for transmitting telephone calls. The caller's voice is changed into a digital signal and used to make the beam of light from a laser switch on and off thousands of times everysecond.
Optical fibers are useful for doctors to look inside the human body without using surgery. The Optical fibers are very thin and are inserted into the body to transmit a picture of the related organ.
What is mining?
Mining is the extraction of materials from the earth. It dates back to ancient times, when people extracted precious stones, copper and silver. Now, of course, mining is done in a more mechanised way.
There are many ways of mining, depending on the nature of the mineral deposit and its depth.
Minerals that lie near the surface can be extracted by open cast mining or quarrying. it is done by blasting the surface with explosives or dragging buckets across the ground to scrap away the soil.
If the material is cut of the ground in long strips, the mine is called a stripmine. Deposits on the bottom of a lake or river are removed by dredging. Drift mining and shaft mining are used to reach deeper deposits. Natural gas and oil are extracted by drilling.
WHAT IS MASER?
Maser stands for Microwave Amplification by Stimulated Emission of Radiation. It produces an intense beam of energy. Produced first in Bell Laboratories in the United States in 1956, a maser produces waves at a frequency.
It can also be used as a clock. In a maser, atmos are excited by firing bursts of energy at them. Excited atmos lose their energy and return to their original state. Microwaves are released as the atom changes from one energy level to the other.
Masers are used as amplifiers in satellite communications and radio astronomy. Laser is the optical equivalent of maser.
What is a magnetometer?
A Magnetometer is a device which is used to measure the strength of a magnetic field. A simple magnetometer is a small coil of wire, which when moved through a magnetic field, produces an electric voltage.
Measuring this voltage indicates the strength of the field. Senstivie magnetometers can measure weaker magnetic fields. They can be towed behind aircrafts to measure slight changes in the earth's magnetic field.
These changes help to locate deposits of iron, oil and resources.
Super conducting magnetometers are used to measure small magnetic fields in the human body.
Magnetic tape is a strip of flexible plastic with a magnetic coating that is used to record sound and pictures. To make a recording, the tape is wound around the recording head which is, in fact, an electromagnet.
The magnetic field it produces varies with the sounds or pictures that created the field. The changing field moves magnetic particles in the tape as it passes along the head. Befor recording , the particles have a random arrangement, But once the recording is done the particles have a regular pattern, corresponding to the recorded signal. When the recording is played, the pattern of magnetic particles in the tape makes eletric currents flow in the head that match the currents that created them.
0 comments:
Post a Comment