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Friday, 26 March 2021

Branches of Medical Treatment

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Here are a list of branches of medical treatment are as follows,


In 1847 and 1848, a Scottish doctor named Sir James Y Simpson used chloroform to relieve the pain of childbirth. Queen Victoria was one among the first to be anesthetized during childbirth. Without anesthesia, doctor can’t do complicated surgical operations. As the anesthetic makes the patient to not suffer from pain, it deeply lessens the physical shock and emotional stress during the operation. General anesthesia involves the loss of feeling in the whole body while local anesthesia is the loss of pain sensation in any of the part of the body.


Cardiology is the branch of medicine that deals with diagnosis and treatment of heart disorders. Doctors who specialize in cardiology are called cardiologists. Cardiologists interview and examine patients for possible heart disease. First, the cardiologist asks if the patients has experienced symptoms that suggest heart disease such as chest pain, shortness of breath, and ankle swelling. The cardiologist then examines the patient by checking the blood pressure, by feeling the beat of the heart and checking the pulse.


It is the branch of medicine that deals with the prevention, diagnosis and treatment of skin diseases. Doctors who specialize in this field are called dermatologists. Skin ailments treated by dermatologists include inflammations, infections, burns and tumours. Dermatologists also treat many children and teen-agers who have acne or certain allergies. Dermatologists are trained to recognize changes in the skin that indicate a disease in other parts of the body.

Forensic Science

Forensic science generally is interpreted as the application of science to legal matters, most often to criminal cases. Forensic medical science dates back to the Greeks. In the U.S it began in 1812 in New York City at the college of physicians and surgeons. Later in the 19th century, Alphonse Bertillon (France) established a system based on measurements of the human body. In 1869 the value of fingerprints was established by Sir William Herschel (England).


The history of Neurology started in 1760's with the publication of work of Swiss physiologist Albrecht von Haller's book on the topic, human physiology. In this book he discarded popular notions about nerves in favor of data he gained experimentally. He proved, for instance, that stimulus to a nerve produced a sharp muscle contraction and thereby demonstrated that nervous stimulation controlled muscle movement. He also showed that nerves channel and carry impulses that produce sensation in tissues.


Ophthalmology is the field of medicine involving the diagnosis and treatment of eye diseases. An ophthalmologist, sometimes called an oculist, must have a medical degree and three to five years of specialized training in a hospital. Ophthalmologists limit their medical practice to the eye. They examine the eye with special equipment and determine the degree of refraction in the lens of the eye. Refraction is a measurement of the eye's ability to see. If the examination shows that the patient needs glasses, the ophthalmologist gives the patient a prescription for them. Glasses are made by an optician. An ophthalmologist who discovers that an eye condition requires corrective surgery is qualified to perform the necessary operation. Albrecht Von Graefe (Germany) is known as the founder of modern ophthalmology because of his contribution during the mid 1800's.


Optometry is a profession devoted to the care of vision. Optometrists give eye health and vision examinations. They diagnose vision problems that affect a persons ability to see near and distant objects clearly and to judge distance. They also test the ability of the eyes to work together ana to change focus easily Optometrists prescribe eye glasses and contact lenses to correct faulty vision. They also may recommend vision therapy to help a person overcome certain vision problems. If an optometrist diagnoses symptoms that indicate disease in the eye or any other part of the body, the person is referred to a doctor.


Orthodontics is the branch of dentistry in medicine that deals with the prevention and correction of irregular positions of the teeth. In addition to causing poor personal appearance, irregularly positioned teeth are difficult to clean. Thus, they are more likely to decay and promote gum diseases. They also can cause chewing and speech problems. Irregularities in the position of teeth are called malocclusions. Malocclusions usually arise during childhood as the teeth grow. They most commonly occur when the teeth are too large for the available law space. Under such conditions, the teeth become crowded and turned out of position. In some cases, one of the jaw bones is larger than the other, creating a condition of overbite or under bite. Malocclusions can sometimes be prevented by the early removal of certain deciduous teeth.


Orthopaedics is a branch of medicine that deals with treatment of disorders of bones and muscles and their related tissues. Doctors who practice orthopaedics are called orthopaedic surgeons. They treat a wide range of disorders including fractures and injuries to ligaments, tendons and so on. They also treat the deformities of the limbs and spine. Some orthopaedic disorders are present at birth. Others occur during childhood due to problems of growth or in later life as a result of aging. Still others result from injury or illness. People injured in car accidents and athletic or recreational activities account for a large number of the patients treated by orthopaedic specialists.


Osteology is the science related with the structure and function of bones. Osteologists study the bones of human beings and animals. They can determine the sizes and living habits of prehistoric animals from bones. They also can tell the age, sex, height and weight of the person or animal from which the bones came. Osteology also includes the study of bone disorders and diseases.


Pathology is the study of disease or any condition that limits the power, length or enjoyment of life Comparative pathology compares human diseases with those of various animals. Human pathology is a branch of medicine. Pathologists use modern instruments and methods, such as electron microscopy, to help them recognize the changes caused by disease in the tissues and organs of the body. They try to explain why a diseased body acts differently from a normal body Pathologists use their knowledge of diseased tissues and body fluids to aid treatment. Pathological tests help doctors diagnose a disease and to establish the extent of its attack. These tests may include examination of the blood, urine and tissues. The use of laboratory tests to diagnose disease is called clinical pathology.

Plastic Surgery

Plastic surgery is a branch of medicine that deals with the repair or reshapes the defects of body. It includes repairing the muscles, bones, nerves and blood vessels. The origin of word plastic comes from a Greek word that means shape or mould. Plastic surgeon moulds the body tissues. They rearrange, take away or replace tissue to reinstate normal function to deformed or injured body parts. Plastic surgeons also attempt to recover the look of aging tissue.

Sports Medicine

Sports medicine is a field that provides health care for physically active people. Its main purpose is to minimize the risk of injury and to treat effectively injuries that do occur. Sports medicine draws on the knowledge of many specialists, including doctors, athletic trainers, physiologists and physical educators. These professionals’ help in shaping the kind of training required to help athletes carry out their top abilities without injury. They also evaluate coaching methods, the enforcement of regulations to prevent injuries and the design and use of athletic equipment and facilities.


Surgery is the branch of medicine that deals with the treatment of disease, deformities or injuries by operations. The doctor who performs the operation is called a surgeon. Every doctor has some training in surgery and is qualified to perform simple operations. But surgeons are specially trained so that they have the judgment and skill to perform complicated operations. Four to seven years of training after medical school are necessary for doctors to qualify as surgical specialists.

Veterinary Medicine

Veterinary medicine is the branch of medicine that deals with the study of diseases of animals. Animal doctors are called veterinary surgeons or vets. Their work is especially valuable because many animal diseases can be transmitted to human beings. Such diseases are called Zoonoses. They include rabies, brucellosis, tuberculosis, psittacosis.

Wednesday, 24 March 2021

List of Biomedical Devices

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Here are a list of biomedical equipment used in Hospitals,

Electrocardiograph (ECG)

Electrocardiograph (ECG) is an instrument used to diagnose heart disorders. For each time the heart beats, ECG produces the electrical currents. Through these currents, we can examine the rate and pattern of contraction of the heart. An electrocardiograph picks up these currents and records them on paper. The electrocardiograph may be connected to a printer, which prints the record. This record is called an electrocardiogram, often abbreviated to ECG. The electrocardiograph may also be connected to an oscilloscope, an instrument that displays the currents on a TV-type screen. An electrocardiograph contains amplifying and recording equipment. Wires run from the machine to electrodes-strips of metal that conduct electricity. In 1903 Dutch physiologist Willem Einthoven invented the first crude electrocardiograph in the form of a string galvanometer. He was awarded the 1924 Nobel Prize in medicine and physiology for this work.

Electroencephalograph (EEG)

Electroencephalograph is an instrument used to measure and record the electrical voltages produced by neurons in the brain. A recording of this electrical activity is called an Electroencephalograph. Doctors and neuroscientists use the electroencephalograph to study normal brain activity, as well as abnormal brain states that caused by injury, tumour, infection or even death. To record an electroencephalogram, medical personnel attach electrodes from the electroencephalograph to the patient's scalp. Hans Berger, a German psychiatrist invented the first electroencephalograph in 1929 to measure the rhythmical electrical activity of the human brain


Thermometer is a biomedical device that measures the temperature of solid, liquid and gases. The action of a thermometer is based on the fact that certain measurable physical characteristics of substances change when the temperature changes. These characteristics include the volume of a liquid and the length of a solid. Another is the resistance - that is, the opposition to the flow of electricity - in an electrical conductor. There are three principal types of thermometres: (1) liquid-in-glass, (2) deformation type and (3) electrical. Many types of thermometers are made as both digital thermometres and disposable thermometers.


Syringe is a pump-like device. It is a tube, tapered at one end, with a plunger or a soft, hollow bulb at the other. The plunger or bulb either creates suction or forces fluid from the syringe. Syringes are used to spray or inject liquids or to remove them by suction.


Spirometer is an instrument that measures the amount of air a person breathes. Doctors use spirometers mainly to diagnose the certain respiratory disorders and to evaluate treatment. A common type of spirometer consists of two cylinders, one filled with air and the other with water. Both cylinders are open at one end. The air-filled cylinder, which is attached to weights, floats open-end down in the water-filled cylinder. The patient breathes through the mouth into a tube extending from the air cylinder. When the person exhales, the amount of air in this cylinder increases and the cylinder rises in the water. As the patient inhales, air leaves the cylinder and it falls. The movement of the air cylinder provides a measure of the volume of air breathed and is recorded on a strip of paper called a spirogram.


The first catheter was made in 1929 by a German physician named, Werner Theodor Otto Forssmann. He made it with a thin rubber tube.  It was intended to examine the diseased hearts. In 1936, other physicians of United States named Dickinson W Richards and Andre F Cournand make developments on Forssmann's catheter and experimented on animals. But the first successful human cardiac catheterization was happened in 1941 under the control of physicians named, Richards and Cournand. The catheter can measure the rate of flow of blood, oxygen and also the blood pressure.


Humidifier is a biomedical device which increases the amount of moisture in indoor air or a stream at air. The working principle of Humidifier is by letting water to evaporate from a pan or from a wet surface or by circulating moisture in air. Humidifiers are used in industry to create an atmosphere suitable for testing or processing certain materials. In homes, humidifiers help reduce static electricity and prevent wood structures and furniture from becoming brittle.


Ophthalmoscope is an optical instrument used for examining the interior part of the eye. Ophthalmologists and optometrists can diagnose many eye conditions by using the ophthalmoscope to examine abnormalities in the eye. There are two main types of ophthalmoscopes. They are the direct ophthalmoscope and the indirect ophthalmoscope. The direct ophthalmoscope contains a light, a prism and a mirror and lenses. These parts are mounted in the head of the instrument, which is attached to a handle containing a battery. The prism and mirror project the light on the back of the eye. The lenses enable the examiner to focus the light to provide a clear, magnified view of the eye's interior. The indirect ophthalmoscope consists of a light worn on the examiner's head and a lens held in front of the patient's eye. This instrument enables the examiner to see a larger area than the direct ophthalmoscope does, but with lower magnification. The ophthalmoscope was invented in 1851 by German physician and physicist Hermann Ludwig Von Helmholtz for the purpose of examining the interior of an eye through its pupil.

Pace Maker

Clarence Walton Lillehei, an American physician built the first pacemaker in 1957. Lillehei’s pacemaker was an electric unit that could be inserted in the patients chest where it would give off an electrical jolt in order to regulate the pace of the heart beat.


In 1863 French physiologist Etienne Jules Marey invented the first sphygmograph for the purpose of recording blood pressure. An external sphygmomanometer that allowed the measurement of blood pressure in clinical settings was developed in 1896 by Scipione Riva-Rocci (Italy).


The sphygmometer was invented in 1835 by French physician Julius Herisson. It transmitted impulses from the pulse beat to a mercury column and made each beat visible to the observer. Herisson 's sphygmometer was the first tool to visually show and numerically measure the pulse beat without the need to puncture an artery.


To aid his research on the mechanics of the cochlea, Hungarian-born physicist Georg Von Bekesy (U.S) developed an “audiometer” during the 1960s. Designed to test the hearing function, it was able to distinguish between deafness caused by functional loss in the cochlea and that caused by a problem with the auditory nerve.


Centrifuge is an instrument used to separate two liquids mixed together, or solid particles that are mixed with water or any liquid. The centrifuge causes the heavier liquid or the solid particles to move to the bottom of the container, leaving the lighter substances on the top. It usually consists of a large wheel connected to an electric motor. The mixtures to be separated are balanced in containers on each side of the wheel. When the motor is turned on, the wheel rotates rapidly and the containers swing out from the centre. A smaller centrifuge consists of a small rotating top in which test tubes of material can be placed at an angle. The centrifuges turn from 800-6000 times per minute. The ultra centrifuge is a newer kind of centrifuge with tremendous speed. It can spin at around 80,000 turns per minute. The rotating part of an ultra centrifuge touches nothing solid. It is balanced on a cushion of air. The ultra centrifuge whirls by means of jets of compressed air that touch the outer surface. Ultra centrifuges are used to study viruses.


Endoscope is a medical instrument used to determine the interior part of a hollow organ or a cavity of body. Unlike other devices, endoscopes are put directly into the organ or cavity that is to be examined. There are several types of endoscopes. Most endoscopes consist of a flexible or rigid hollow tube with a lens at one end. Arnaud designed the first endoscopic lamp used to illuminate the interior of orifices in humans around 1819. He built his instrument with a biconvex lens.


Incubator is an apparatus that maintains a favorable environment for growth and development. Some types of incubators are used by hatcheries to hatch chicks from eggs. Others are used in hospitals to maintain the lives of newborn or prematurely born babies. Some are used in laboratories for research. All these incubators differ in design, but their chief function-to provide a controlled environment - is the same. In 1884 an incubator warmed by Kerosene lamps appeared in Paris at La Maternite. American physician Julius H. Hess designed an electric incubator for premature infants and filed for a patent in 1933.


Microscope is an instrument that magnifies extremely small objects so they can be seen easily. It is one of the most important tools for diagnostic purposes. For instance, Doctors and biologists, use microscopes to determine bacteria and blood cells.



In 1854, a music teacher named Manuel Patricio Rodriguez Garcia from England developed the first laryngoscope that permitted a clear view of glottis at work. Garcia found that the vocal cords are the reason for the voice and its tones. With this laryngoscope, it became possible to see any obstacles occurring in the larynx.


An instrument doctors use to hear the sounds produced by certain organs of the body, such as the heart, lungs, intestines, veins and arteries. The stethoscope picks up the sounds made by these organs and excludes other sounds. Listening in this way, known as auscultation, is an aid to diagnosis. It alerts the doctor to characteristic changes of sound caused by different types of diseases. The stethoscope consists of a body contact piece, which is placed against the body of the patient and ear pieces, which are placed in the ears of the doctor. Hollow rubber tubing connects the body contact piece to the ear pieces. Doctors use either a bell, diaphragm or combination bell-diaphragm body contact piece. The bell type of contact piece picks up low-pitched sounds. The diaphragm type picks up high-pitched sounds. Rene Laennec a French physician, made the first stethoscope in 1816.


In 1626 Italian physician Santorio Santorio, also known as Sanctorius, adapted the thermometer invented by Galileo Galilei (Italy) in 1593 for the purpose of measuring human temperature in a clinical setting. Santorio's device was called a “thermoscope".


Ventillator is a machine that helps a person breathe. A ventillator may be used if illness or an accident causes breathing to become difficult or to stop. It also can be used to administer oxygen or to treat a patient with a mist containing medications. Ventillators are often called respirators or resuscitators. There are two basic types - positive pressure and negative pressure ventillators. A positive pressure ventillator forces air into the lungs under pressure. After the lungs are filled, the machine cuts off the pressure and the natural elasticity of the lungs expels the air. Such machines operate as either assist ventillators or automatic ventillators. Assist ventillators are triggered by the patient's breathing. They help extremely weak people inhale. Automatic ventillators control respiration completely and aid people whose breathing muscles are paralysed.

Monday, 22 March 2021

Electrical and Electronic measuring Instruments

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Some electrical and electronic measuring instruments are given below.


Ammeters are instruments for measuring electric currents. They have an electromagnet and a permanent magnet, either one of which is movable, although the moving coil type is more uneven. They are not as sensitive as galvanometers due to their design, which causes only a small proportion of the current to flow through the coil. The first one was invented in 1820 by Hans Christian Oersted (Denmark).

Electric Meter

Electric meter is an electrical device which is used to measure the electric current. Electricity Service Provider use watt-hour meters to evaluate in kilowatt-hours the amount of electrical energy consumed by their users. A kilowatt hour has 1000 watt-hours. For example, if Ten, 100 watt light bulbs operated for one hour will consume 1 kilowatt-hour of electricity. The electricity service provider connects the meters to the lines that supplies electricity to households or industries. The staff from electricity service provider reads the meter at regular intervals between one or more months and will give the customer’s bill based on these readings.


Galvanometer is a delicate electrical instrument used mainly to detect and measure small electric currents. Most galvanometers operate on the principle that an electric current flowing through a wire in the presence of a magnetic field produces a force on the wire. A typical galvanometer has a scale with a zero in the centre and numbers at regular intervals on either side. It also has an indicator such as a needle or a beam of light. The indicator remains at zero until a current passes through the galvanometer. A current in one direction causes the indicator move to one side of the zero point. The first galvanometer was invented by Hans Christian Oersted (Denmark) in 1820. The first moving coil type was devised in 1825 by Johann Schweigger (Germany) and in 1828 C.L. Nobilli (Italy) designed an astatic type. A galvanometer with a mirror, making it very sensitive, was invented in 1867 by Lord Kelvin (Scotland).


Oscilloscope is an electronic instrument that displays changing electrical signals. The signals appear as straight or wavy lines or in other patterns on a fluorescent screen. Oscilloscopes are used in such fields as industry, medicine and scientific research. Electronic engineers use the instruments to test computers, radios and other electronic equipment. Doctors use them to study electrical impulses from the brain or heart. Light, mechanical motion and sound can be studied with oscilloscopes. Devices called transducers change these forms of energy into electrical signals. The screen of an oscilloscope is the front of a cathode-ray tube, a special type of vaccum tube. Inside the tube, a device called an electron gun projects a beam of electrons on to the fluorescent screen. A circuit called the time base causes the beam to move repeatedly from left to right. It was invented in 1897 by Karl Ferdinand Braun (Germany).


Potentiometer is a device that measures electric current, voltage and resistance with high precision. It shows voltage differences by comparing an unknown electromotive force with a known one. It is used to calibrate voltmeters or ammeters and as a control element in electronic circuits and devices.


Tachometer is a device that is used for measuring the speed of rotation of a spinning shaft or wheel, usually in terms of revolutions per minute (rpm). Tachometer’s often are used to measue engine rpm in cars, ships and aircraft. Tachometers indicate an engine’s power and its efficiency in converting energy into mechanical force. The drag-type tachometer is widely used in cars. A digital tachometer measures rpm by means of a pulse accompanying each rotation of the crank shaft. An electric tachometer is commonly used in airplanes. Reed tachometers are used on steam turbines and large engines.


Speedometer is an instrument that indicates the speed of a car or other vehicle. The speedometer display may show speed in kilometers per hour, miles per hour or both. There are two types of speedometers: (1) mechanical speedometers and (2) electronic speedometers. A mechanical speedometer indicates speed by means of a dial and a pointer. This type of speedometer is driven by a flexible shaft connected to a set of gears in the vehicle’s transmission. An electronic speedometer consists of a speed-sending unit, a signal conditioner and an electronic digital or analog readout.


The device that increases or decreases the voltage of alternating current can be termed as a transformer. In order to change such voltage, transformers provide a simple, inexpensive way. Electric power companies mainly depend on transformers to transmit alternating current effectively. The circuits such as: home appliances, lights, industrial machinery and other electric equipments ensure proper voltages. Most transformers are made up of two insulated wire coils. One coil, referred to as the primary winding, is attached to the voltage source to be modified. This voltage is the transformer's input voltage. The output voltage is supplied to the desired circuit by the other coil, known as the secondary winding. The primary and secondary windings of most transformers are wrapped around a hollow core made of thin iron or steel sheets. The majority of cores are shaped like a ring or a square. There is no relation between the two coils.


Transistor is a tiny device used in computers, radios, television sets and other electronic equipments. Transistors control the flow of electric current in such equipment. A typical transistor, together with its protective case, is about as large as the eraser on a pencil. Electronic equipment has been revolutionized by transistors. In modern electronic equipment, most transistors are packaged inside devices called integrated circuits. There may be hundreds of thousands of transistors in just one integrated circuit about the size of a postage stamp. Without transistors, companies can’t make pocket calculators or other high-speed computers. Battery worked radios and television would be much larger and highly expensive.


Voltmeter is an instrument that measures the voltage between two points of an electric current. Most commercial voltmeters are galvanometers connected in series with a high resistance. They have scales that read in volts. A typical direct current voltmeter has a magnet shaped like a horse shoe. To each pole of the magnet is attached a semicircular piece of soft iron that also becomes magnetized. These pieces of soft iron direct the magnetic field toward a small iron cylinder placed between the poles of the magnet. Since soft iron becomes highly magnetized, this cylinder concentrates the magnetic field. Voltmeter was invented in 1820 by Hans Christian Oersted (Denmark). The digital style meter was invented in 1952, it uses solid state circuits. Around 1970 integrated circuits were introduced, for use when high accuracy is required.

Friday, 19 March 2021

Atmosphere Layers of Earth

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The gaseous (air) covering surrounding the earth is called earth’s atmosphere. The earth’s atmosphere mainly consists of nitrogen (78%) and oxygen (21%). In addition to this a very small amount of argon, carbon dioxide, water vapour, hydrocarbon, sulphur compounds and dust particles are also present.


As we go up, the density and pressure of the atmosphere rapidly decrease. At 100 km height from the earth surface, the pressure is only 10-3 mm which is same as the vacuum attainable in the laboratory by a good vacuum pump. The mean free path of a molecule in this region is 10-4 in as compared to 10-7 m near the ground.

The earth's atmosphere is divided into four regions; (1) Troposphere (2) Stratosphere (3) Mesosphere and (4) Ionosphere based on the mode of temperature control. There is no sharp boundary between the regions.


1. Troposphere: 

Troposphere is the layer of the atmosphere closest to the earth. We live there and nearly all the earth’s weather occurs there. The upper boundary of the troposphere is called the tropopause. The tropopause lies about 16 kms over the equator and about 10 kms over the North and South poles. The stratosphere lies above the troposphere, followed by the mesosphere and the thermosphere. Within the troposphere, the temperature of the air generally decreases as the altitude increases. The temperature of the troposphere also varies with latitude. Troposphere region extends upto a height of 12 km from the surface of earth. The solar radiation which is responsible for heating of the troposphere by conventional air current is in the infrared, visible and ultraviolet region. In this portion of the atmosphere, the average temperature decreases with height from 17°C to —53°C. At the equator, the tropopause can as cold as –80°C. Above the tropopause, the temperature stops decreasing with altitude.


2. Stratosphere: 

In 1902 the French meteorologist Leon Teisserene de Bort proposed that the atmosphere is divided into two parts, with the lower layer containing all the weather activity (such as rain, clouds, winds). He called this the troposphere and the higher layer he named the stratosphere, beginning at 25,000 feet at the poles and 50,000 feet at the equator. The boundary between the two he called the tropopause. Stratosphere extends from 12 km upto 50 km from the surface of earth. Solar radiation is the controlling factor of temperature. The temperature of this region varies from —53°C to 7°C. At the base of the stratosphere the temperature is almost constant with height. In the stratosphere at a height of 15 km from the surface of the earth, the density is about one-eighth of that at the ground. From spectroscopic studies, Hartley concluded that Ozone (O3) is present in the stratosphere and it is concentrated in the region near 25 km to 50 km from the surface of earth. This region is called Ozone layer. It is this ozone layer which absorbs large portion of uv radiation emitted by the sun.


3. Mesosphere: 

Mesosphere is a layer of the earth’s atmosphere. It lies between the stratosphere and the thermosphere, the upper most layer of the atmosphere. This region of atmosphere extends from 50 km upto 80 km from the surface of the earth. Mesosphere is very cold. The temperature of the air in the mesosphere generally decreases as the altitude increases. The temperature of this region fluctuates from 7°C to -93°C. The lowest temperature in the earth’s atmosphere occurs at the top of the mesosphere called the mesopause. In the mesopause over the North and South poles, the air temperature may drop as low as –109°C. Shooting stars burns up here. The coldest mesopause temperatures at a pole occur when it is summer there.


4. Ionosphere:


Ionosphere is a part of the earth’s atmosphere that has many ions and free electrons. Cosmic rays and radiation from the sun produce those ions. The ionosphere extends through the layers of the atmosphere known as the mesosphere and the thermosphere. Several ionized regions make up the ionosphere. The lowest one, called the D region, begins at an altitude of 55 to 89 kilometres. The F region begins at 80 kilometres and extends up to about 400 kilometres. The height and ionization of these regions vary from day to night and with changes in solar radiation. For example, the D region almost disappears at night. The other regions rise and become less strongly ionized at night because no solar radiation reaches the atmosphere. In 1902 Kennelly in America and Heaviside in England almost simultaneously postulated the existence of this conducting layer in the upper atmosphere. By the ionisation action of solar radiation positive and negative ions are produced in the atmosphere which reflect the radio waves (wavelength around 10 metre). Later Ionosphere was discovered in 1922 by English physicist Sir Edward Appleton. In 1924 he located and measured the reflecting layer, the Kennelly-Heaviside layer, about 65 miles high. He named that part of the atmosphere the ionosphere because of the high number of ions present there.  The temperature of this region varies from —93°C to 427°C. Ionosphere plays a fundamental role in the propagation of radio waves round the curved surface of the earth. But for the ionosphere long distance communication would have been an impossibility before the launching of satellites.


Note 1: The different regions of our atmosphere affect us differently. For troposphere temperature decreases with height. For stratosphere, mesosphere and ionosphere temperature increases with height.


Note 2: Ozonosphere: The upper region of stratosphere contains ozone (O3) in abundance. This region is called ozone layer. Ozone in this region absorbs ultraviolet radiations coming from the sun and hence the humanity is saved from the ill effects of the ultraviolet rays from the sun. Absorption of ozone in the visible region is extremely small.


The atmosphere permits the life giving radiation to pass through it, but provides a protecting cover from the harmful radiations such as X-rays, ultraviolet rays etc. These radiations are absorbed by the ozone layer. Energy from the sun heats the earth which itself radiates infrared radiation. However earth being at a lower temperature emits infrared radiation of longer wavelength. These are unable to cross the lower atmosphere as it reflects them back. On this account earth's atmosphere is richer in infra red radiation or thermal radiation. Low lying clouds too prevent escape of infra red radiation thus keeping the earth warm. This phenomenon is called green house effect.

Tuesday, 16 March 2021

Merge Sort and Insertion Sort

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One of the most effective sorting algorithms is merge sort. The merge sort also follows divide and conquer approach as in the case of QuickSort. It splits the input array in half, calls itself for each half, and then combines the two sorted sections. If we want to merge an array of ‘n’ elements, we will first split that array into two. Consider the array A[n], the split is done as A[1...(n/2)] and A[(n/2)....n]. Then again splits these arrays until it reaches a single element. Then sort the two sub arrays and merges it using a function. Merge sort continuously cuts down a list into several sublists until each sublist contains just one variable, then merges those sublists into a sorted list.


Working of Merge Sort


Top-down attempt


The recursion mechanism is used in the top-down merge sort technique. It starts at the top and works its way down, with each sequential turn saying the same thing, such as “What is needed to sort the array?” and the solution being “split the array into two, make a recursive call, and combine the results.”


Consider the below given situation


1. Separate the unsorted collection into n sublists, each with one variable (a list of 1 element is supposed sorted).

2. Merge sublists repeatedly to create newly ordered sublists until only one sublist remains. The ordered list will be shown below.


The merging is done in the following manner


Both lists' first item is compared. As two elements are ordered in ascending order, the smaller of the two becomes a new element in the sorted list. Finally all the sublist will be vacant and the merged list will contain all the elements that contained in the sublist earlier.

Bottom-Up approach in merge sort operation

Iterative technique is used in the Bottom-Up merge sort strategy. It begins with a “single-element” sequence and then blends two adjacent elements while still sorting them. The combined-sorted arrays are combined and sorted again until only one single unit of sorted array remains.

1. Combine two arrays of the same dimension (Iteration 1)

2. In the second iteration merge the above arrays of size 2

3. 3rd iteration

Finally we get the sorted list.




In this mechanism one element is considered at a time and sort it in its correct position. The array elements are sequentially compared and then placed in a certain order simultaneously. The example can be seen in the way a deck of cards is organised. The name Insertion Sort comes from the fact that it operates by adding an entity at a specific location.


Working of Insertion Sort


The first step is to compare the element in question to its neighbouring element.

For each analysis shows that the element in question may be inserted in a specific location, space is generated for it by moving the other elements one place to the right and placing the element in the proper location.

The operation is repeated until all of the array's elements are in their proper positions.


It iterates through the input elements, growing the sorted array each time. It compares the current variable to the sorted array's largest value. If the current element is larger, it remains in place and goes on to the next element; otherwise, it locates the element's right location in the sorted list and moves it there.

Consider the array A=[7, 4, 5, 2]

Since 7 is the first entity, there is no other element with which it can be compared, it remains in its original place. Now, as we get closer to 4, the largest factor in the sorted list is 7, which is greater than 4. As a result, shift 4 to its proper location, which is before 7. Similarly, we can shift 5 to its proper location since 7 (the largest factor in the sorted list) is greater than 5. Finally, since all of the elements on the left side of 2 (sorted list) are greater than 2, all of the elements on the left side of 2 are pushed one step ahead, and 2 is put in the first position. Finally, a sorted array will be generated from the specified array.

Friday, 12 March 2021

Electromagnetic Spectrum - Types and Uses

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The orderly distribution of electromagnetic radiation from gamma rays of very short wavelength to radio waves of long wavelength is known as electromagnetic spectrum. The types and uses of electromagnetic spectrum are explained below.



■ Frequency range – 3 x 103 to 3 x 1011 Hz

■ Wavelength – 10-3 to 105 m

■ Production – Oscillating circuits (Tank circuits)


They are produced by oscillatory LC circuits. The range of wavelength is between a few metres to a few hundred metres. They are used for radio communication. Radio waves are in the frequency range from 500 kHz to about 1 GHz. The amplitude modulated (AM) band is from 530 kHz to 1710 kHz. Higher frequencies upto 54 MHz are used for short wave (SW) band. 54 MHz to 890 MHz are used for TV transmission. The frequency modulated (FM) radio-band is from 88 MHz to 108 MHz. The cellular phone uses radio waves in ultrahigh frequency (UHF) band.




■ Frequency range – 5 x 109 to 1012 Hz

■ Wavelength – 3 x 10-4 to 6 x 10-2 m

■ Production – Klystron, Magnetron


The wavelength range is between 10-3 m to 0.3 m. The frequency range is from 300 GHz to 1 GHz. They are produced by specially designed oscillators. They are used in communication for transmission of radar and TV signals. They are used in satellite communication. Microwaves are often used to transmit telephone conversation. Microwave ovens are used as domestic appliances. 


Uses of microwaves


1. Microwaves are used in radar systems.

2. They are used in the study of atomic and molecular structure.

3. They are used in aircraft navigation.

4. They are used in microwave ovens.

5. Microwaves are used in satellite communication.

6. Cable TV, Internet and cellphone networks use low frequency microwaves.


Microwave Oven: Atoms and molecules of a substance possess kinetic energy of translation, rotation and vibration. When kinetic energy of the atoms and molecules increases, the temperature of the substance increases and the substance becomes hot. Most of the food items such as vegetables, fruits, meats, cereals, etc., contain water as a constituent. The frequency of rotation of water molecules is about 3 GHz which corresponds to microwave frequency. If these molecules receives microwaves of this frequency, the molecules absorb the radiation, resonance occurs and the molecules rotates violently. The kinetic energy of molecules increases. Thus the food items which contain water get heated up and cooked.




■ Frequency range – 1012 to 4 x 1014 Hz

■ Wavelength – 8 x 10-7 to 3 x 10-4 m

■ Production – Excitation of atoms and molecules


The wavelength of infrared radiation ranges from 0.7 micrometre to about 1.0 millimetre. Warm or hot objects and the sun emit infrared radiations. Low temperature bodies emit long wavelength radiations, whereas high temperature bodies emit short-wavelength radiations. An increase of temperature is observed when infrared radiations are absorbed by matter. For example infrared rays falling on the skin produce the feeling of warmth. Blackened thermometer, photo transistor and photographic film detect these radiations. Glass is opaque to infrared radiations and hence rock salt prisms and lenses are used in spectroscope for the study of infrared radiations. Infrared radiation are produced by excitation of atoms and molecules. Hot objects like red hot iron, filament of the lighted electric bulb, sun, stars, etc emit infrared radiations.


Uses of infrared radiation


Infrared radiations are used

1. In night vision devices as they can pass through fog and mist

2. to keep the green houses warm

3. to treat muscular strain (using infrared lamp)

4. in solar water heaters and cookers

5. for producing dehydrated fruits

6. in weather forecasting by infrared photography

7. in the study of molecular structure

8. in automatic counters

9. in photocopiers

10. in remote switches and remote control of household electronic systems such as TV sets, video records, etc.

11. and to take photographs in darkness.




■ Frequency range – 4 x 1014 to 8 x 1014 Hz

■ Wavelength – 4 x 10-7 to 8 x 10-7

■ Production – Excitation of atoms, sparc and arc flame


Radiations of wavelength ranging from 0.4 micrometre to 0.7 micrometre are called visible radiations, which our eye distinguishes as colours ranging from violet to red - VIBGYOR. The visible spectrum forms only a small part of a much larger electromagnetic spectrum.


Uses of Visible Radiation


1. Visible light produces sensation of sight in human beings. This enables us to see the world around us. (Many insects can detect uv rays; snakes can detect infrared rays. But human beings cannot see objects with the help of these radiations.)

2. It is used in photography.

3. It is used in optical microscopes and telescopes.

4. It is a great source of energy for human life.




■ Frequency range – 8 x 1014 to 1016 Hz

■ Wavelength – 3 x 10-8 to 4 x 10-7

■ Production – Excitation of atoms and spark


The sun, electric sparks, mercury lamps and very hot objects are sources of ultraviolet radiations. The range of wavelength is from 0.4 micrometer to about 1 nanometer. Ultraviolet radiations produce vitamins in the skin and cause sun-tan. An overexposure to these radiations, especially in the short wavelength region, is harmful. Glass is opaque to ultraviolet radiations whereas quartz is transparent. Fluorescent materials absorb ultraviolet radiations and re-radiate as visible light. Photo-electric devices and photographic films detect ultraviolet radiations.


Uses of ultraviolet radiation


The uv rays are used:

1. to make drinking water bacteria free (in water purifiers).

2. for sterilizing surgical instruments.

3. in detecting invisible writing, forged documents, counterfeit currency notes and finger prints in forensic laboratory.

4. in burglar alarm.

5. for checking the mineral samples as uv rays produces fluorescence.

6. to preserve food stuffs as uv rays destroy germs

7. and for LASIK eye surgery




■ Frequency range – 1016 to 3 x 1019 Hz

■ Wavelength – 10-10 to 3 x 10-8

■ Production – Bombardment of metal target by electrons


X-rays have wavelength varying from 1 nanometre (10Å) to 0.01 nanometre (0.1Å). X-rays are produced by X-ray tubes. They can be detected by photographic films. They are harmful to living tissues. X-rays find wide applications in science, technology and medicine. X-rays are used for studying crystal structure.


Uses of X-ray


1. in medical diagnosis like detecting fracture in bones and foreign materials like metal pieces, bullets in human bodies by taking X-ray photograph.

2. in radio therapy to cure cancer, tumors etc

3. in engineering for locating faults, cracks, flaws, air pockets, etc in metallic structure like girders, railway lines, etc

4. and in customs to detect contraband goods like gold, diamonds, guns, etc, concealed in bags or body of a person.




■ Frequency range – 3 x 1018 to 5 x 1020 Hz

■ Wavelength – 6 x 10-13 to 10-10

■ Production – Nuclei of atoms


γ-rays have wavelength less than that of X-rays and hence are extremely powerful. They overlap the upper limit of X-ray spectrum. Their wavelength ranges from 10-10 m to 10-14 m which corresponds to a frequency range from 3 x 1018 Hz to 3 x 1022 Hz. They are of nuclear origin. Radioactive elements radiate γ-rays. Photographic film, Geiger Muller Counter etc detect these radiations. These rays are more harmful than X-rays to living tissues. In cosmic rays, γ-rays of shorter wavelengths are present.


Uses of γ-rays


The γ-rays are used:

1. for the treatment of cancer and tumors in the body of human beings.

2. for locating cracks, flaws in thick metal structures (as in the case of X-rays).

3. and to get valuable information about the structure of nuclei

Tuesday, 9 March 2021

Quick Sort and Bubble Sort

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Sorting Techniques in Data Structures

Sorting is defined as the arrangement of data in a desired order as per our constrain. The main advantage of sorting is that it makes searching quick and very easy. In computer world sorting algorithms are used to rearrange a large number of elements in a specific order, i.e. from lowest to highest, or vice versa or even alphabetically. These algorithms grasp an input list, perform certain functions (processes) and finally create a sorted list of taken elements.

In day today life we can encounter many situation where we use sorting techniques, for example in an eCommerce website, the items that we search can be arranged in the increasing order or decreasing order of their price. This is done by the sorting techniques.


Types of Sorting Algorithms:


1. Quick Sort

2. Bubble Sort

3. Merge Sort

4. Insertion Sort

5. Selection Sort

6. Heap Sort

7. Radix Sort

8. Bucket Sort




This is generally a divide and conquer algorithm. It selects an element as pintle and distributes the given sequence around the selected pivot. There are different versions of Quick Sort are available on the basis of the way of determining the pivot point.  


Always pick first element as pivot.

Always pick last element as pivot (implemented below)

Pick a random element as pivot.

Pick median as pivot.


Quick Sorting  is a very efficient sorting algorithm and it is based on dividing continuous data into smaller sequences. A large array is divided into two rows, one of which has values ​​less than the specified value, say pivot, from which the partition is created, and the other row has values ​​greater than the pivot value. The QuickSort, first splits an array into two. Then it again calls itself for sorting the two subarrays that divided before. This algorithm works very efficiently in the case of large set of elements.


Quick Sort Algorithm


Again and again we end up with the smallest possible arrays using the running algorithm. Each partition is then processed for quick sort. We define the iterative mechanism for quicksort as follows –


1 − Make the right-most index value pivot

2 − partition the array using pivot value

3 − quicksort left partition recursively

4 − quicksort right partition recursively

Quicksort uses recursion for sorting the sub-parts.


Different phases in the quick sort algorithm



The sequence is divided into subdivisions, where the pivot point is the division point. Elements smaller than the pivot point are placed to the left of the pivot point and elements larger than the pivot point are placed to the right.



The left and right subdivisions are redistributed by selecting the pivot components. This can be achieved by repeatedly passing subdivisions along the way.



This action does not play a significant role in the quicksand. The queue is already sorted at the end of the capture step.


Working of QuickSort


1. First we have to select an element from the array, we call it pivot element. The decision is ours that we can select any of the element from the array as the pivot element.

In this example we are taking the last element as pivot

2. Here the pivot element is ‘2’. Here we compare the other elements in the array with the pivot element and the elements less that pivot element is move to the left side of the array and greater that pivot is put on the right side.

The arrangement shown above is attained by the following steps.

A. At the pivot element, a pointer is fixed. Beginning with the first index, the pivot element is compared to the others. A second pointer is set for the element greater than the pivot element if it is reached.


B. The pivot element is now compared to the rest of the elements (a third pointer). If a smaller element than the pivot element is detected, the smaller element is switched with the larger element discovered earlier.

C. The procedure continues until the second-to-last variable has been reached. The pivot variable is then replaced with the second pointer.

D. The pivot element's left and right subparts are now taken for further processing in the steps below.


3. Again the pivot elements are chosen from the left and right sub-portions separately. Within the subpart , again any pivot element is taken and the element is placed at right most position. Then, second step is repeated.

4. The sub-parts are further subdivided into smaller sub-parts, until each sub-part is made up of only one piece.


5. At last we get the sorted array



It is a simple sorting algorithm. In this algorithm the adjacent elements are swapped repeatedly if they are in the wrong order. This sorting algorithm compares the neighbouring elements and differentiates whether they are in order, if it is not in order the elements are interchanged.  Huge data sets are cannot be processed by this algorithm. Suppose we want to sort an array of N number of elements, this sorting algorithm compares all the elements one by one based on their values.

If an array must be ordered in increasing order, bubble sort will begin by contrasting the first and second members of the array swapping both elements if the first element is greater than the second, and then moving on to compare the second and third elements, and so on. If our array contain total N elements, the we have to do this process N-1 times to sort the complete array. It's called bubble sort because the largest element in the given array bubbles up to the last position or highest index for each complete iteration, similar to how a water bubble rises to the water surface. Sorting is done by going through all of the elements one by one, comparing them to the next closest element, and swapping them if necessary.


Working of bubble sort


1. This sorting technique starts from the first index position. The compares the first element with the second, if the second element is less than the first element, the elements are swapped. Next compares the second element with third element. Swapping is performed if they are not in order. The above process will continue until the last element was reached.

2. For the residual iterations, the same procedure is followed. The largest element among the unsorted elements is put at the end of each iteration. The comparison takes place up to the last unsorted element in each iteration. When all of the unsorted elements have been put in their correct places, the array is said to be sorted.