Children raised in the strictest discipline Sometimes a cowardly

Child's family is socially dignified and financially sound, then the children become talkative, skilled in management, progressive, fall in business, but the effect on the mental development of children from socially weak or poor families is clearly visible. Maui is. In some cases, such children are more likely to become stubborn and stubborn than a child who has grown up in an overly pampered code.

 Children raised in the strictest discipline | Sometimes a cowardly or overly angry killer is killed. If a child is given a proper pampering and disciplined environment and a true understanding of values ​​is measured, all of these things have a lot of positive effects on a child's mental development. A child raised in a clean environment and in the company of nature is open-hearted, healthy and cheerful. Atmospheric pollution has a negative effect on mental development as well as physical development. Such a child is more likely to be accustomed to irritability and blindness.

  If a child gets a harmonious environment in school, if he gets enthusiastic and loving teachers, it will have a very positive effect on the mental health of the child. 

Thee poor mental health of the teacher and the hostile environment of the school have a negative impact on the mental health of the child. Circumstances that have a good circle of friends have a positive effect on the child's mental health in situations where none of his friends have any kind of manners. 

Thee child is more likely to adopt such habits in the company of well-behaved friends and has a detrimental effect on the child's mental health. If the child enjoys playing games, reading new things and spending time with friends, then such a child becomes sociable, adopts new ideas and has a spirit of cooperation. If the child is living alone, spending more time on mobile and television, then such a child is more likely to become stubborn, stubborn and overly angry..

 

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The honor of establishing the relationship of psychology with education goes to the great Swiss teacher and educator Pastellozi.  He can be considered the father of educational psychology.  There have been many experiments and researches in educational psychology from his time till now.  From the beginning of the twentieth century, certain forms of educational psychology have begun to take shape and develop.  As new problems arise in the field of education, the scope of educational psychology expands, as Gates and others say, ‘The questions of the study of educational psychology are systematic and precise.  We cannot limit the field of educational psychology.  The content of Crow and Co educational psychology relates to all the conditions that affect the study, so all the factors related to the study become the field of work of educational psychology.  The subject matter of educational psychology is concerned with the conditions that affect learning, Crow & Crow. 

Douglas and Holland Educational psychology deals with the activity, mental life, and behavior of the person involved in the learning process.  The subject matter of educational psychology is the nature, mental life and behavior of the individual undergoing the process of education. As can be seen from the above, the main focus of the field of educational psychology is the child and the body.  

The child's cheerful demeanor, cognitive development and demonstration are included in the educational psychology along with all the psychological matters. 

 The field of ES Typical Psychology mainly includes the following: Personality development Mental health Individual differences and demonstrations Educational measurement and evaluation in the context of adaptation to the process of learning the innate foundations of human growth and development behavior and impulses

Psychologists of the Twentieth Century will also be Remembered

Psychologists of the Twentieth Century will also be Remembered

In addition to Pearson and Thorndike, Watson, Pavlov, Werdhimer, Kof Ka, and Kohler have also contributed to the field of education through psychological experiments.

 Vardhimer, Kohler and Kofka have contributed to the development of the Gestast theory.

 In the twentieth century, Kurtlevin has expanded new horizons in the field of psychology, with an emphasis on the study of the child's personality and Sigmund Freud's emphasis on the unconscious mind and analysis.

 The contribution of Afrid Adler and Yuga among the important educational psychologists of the twentieth century will also be remembered.

 Thus, educational psychology as an independent branch of psychology has been able to establish itself as an important subject until the development of the twentieth century.

Hence psychology is called the science of behavior.  The current definition of psychology is now generally accepted by all teachers and psychologists. 

 Thus, at the end of the study of psychology from ancient times to modern times, it can be said that psychology is the science of studying human behavior.  In support of this view we will look at the psychology terminology of some psychologists.

Educational psychology is that branch of psychology

Educational psychology is that branch of psychology

Educational Psychology: Historical Background About Educational Psychology Skinner notes that, "Educational psychology is that branch of psychology which deals with teaching and learning." - Skinner Educational psychology is a branch of psychology that touches on teaching and learning. According to Sickner, educational psychology dates back to the time of Aristotle, but Pastellozi, Habante, and Fobel have made important contributions to giving it an important autobiographical form. 

 "In the eighteenth century, Rousseau called for education through individual freedom, self-expression and activity. Pastelology (1746–1827) emphasized the development of knowledge, reasoning power through the senses. Howell (1782–1827) emphasized education through activity according to the psychological needs of children. In the nineteenth century, Darwin made important contributions to the field of educational psychology through the theory of evolution.

 This brought a unique light to the field of biological psychology. Psychologists such as Francis Gatton (1822-1911), Wilhelm Wood (1832-19: 20), and Stanley Hall have made important contributions to the development of academic psychology as a branch. Hulbert Spencer, William James, and John Dewey also made important contributions in the early twentieth century. How important in the field of evaluation and measurement in the last phase of the nineteenth century contributed to psychology.

Spectrometers have been Developed which use Deflection

 Spectrometers have been Developed which use Deflection

Mu-mesons are elementary particles having mass 207 times and charge equal to that of an electron. When a beam of mu-mesons is incident on nuclei like graphite, mu-mesons move in Bohr orbits which have got radius 207 țimes shorter and energy 207 times greater than that of an electron. When these mu-mesons are excited and de-excited, they emit mesonic X-rays.

 The obseryed experimental values of energies of X-rays dépend upon the value of nuclear radius and are usęed to estimate the size of the nucleus. The average value. of nuclear radius found by this method is equal to (1.20 ± 0.03) A x 1015 m.

 Electron Scattering Method The most important method of finding thẻ electric charge distribution inside atomic nucleus is based on the elastic scattering of électrons by nuclei as a function of scàttering angle: The charge distribution in the nucleus is obtained from the best fit to the experimental dáta óf electrons scatteréd in the enèrgy| range from 50 MeV to 1 BeV.

 It gives the following charge distribution p(r) as a function of distance, 'r, from the nuclear.centre:
and'spectrometers have been developed which use deflection of positively charged ions by the applieation of electric and maghetic fields in evacuated chambers to estimate their nueléar mass. Aston's mass spectrograph and Dempster's mass-speetrometër are two typical- instruments which aré described as follows: may.

Focussing device which focuses the particles

 Focussing device which focuses the particles 

Used to estimate the masses of nuclei and relative abundahce of various isotopes, It plays an important role for: accurately estimáting masses of nuclei and atoms, binding energy, nuelear reactions, disintegration studjes and study of other important nuclear properties. The mass spectrometers generally.consist of the following essential components.

An ion source capable of emitting beams of positively charged atomic and molecular particles which äre johized. (ii) Collimatộr slits which limit the beam to a narrow width and accelérate these, (iif) An analyzer which consists of an electric field applied perpendicular to the path of the particle and is used as an energy filter and a magnetic field applied in the perpendicular plane which is used as a momentum filter.

 (iv) Focussing device which focuses the particles of the same mass travelling with a spread of velocities in different directions along the median plane of the beam. (v) Detector consist of a photographic plate which may carry the image of ions in a masSS spectrograph or an electrode connected to a sensitive electrometer which collects pulses of current produced by a number of ions falling on it pér unit. time. A numbèr of mass spectrographs .

Density of nuclear matter cup be Estimated

  Density of nuclear matter cup be Estimated 

Various nuclei. Ahe density of nuclear matter cup be estimated from the ratio of nuclcar ss and nuclear volume and is of the order of about 2 x 10" kg/m which extremely high. The density of some of stars like white dwarfs is also very high and is cómparable to the density of nuclear matter, oment, This is also confirmed from other static and dynamic properties 1.3 Nuclear Mass The nuclear nass had been éarlier estimated in terms of atomic mass- unit which was defined as egual to 1/16th of mass of neutral O0 isótope whose mass was taken exactly equal to 16.00.

 Ho ver, International Union of Pure and Applied Physics adopted a differe, unit of mass in 1960 which was defined as thất unit of mass which is equal to 1/12th of mass. of C4 heutral isotope whose imass was taken exactly equal to 12.0000. The atomic mass.

 Unit is equal to 1.66043 x 10 27 kg. The masses of all the nuclei and atoms are now expressed in terms of this atomie mass unit. The,mass of proton and neutron on this scale is 1.007277 and 1.008665 mass units, respectively, The mass of hydrogen atom, which is equal to the sum of mass of a proton and an electron, is h007825 mass units. The equivalent energy, Moc produced due to conversion of 1 atómic mass unit, (amu), is equal to 1.66 x 10:21 x (3 x 10, i.e. 1.49 x 1010 Joules or about 931 MeV. Mass spectroscopic techniques are.

Neutron by emission of positron and a neutral particle of negligible mass

Neutron by emission of positron and a neutral particle of negligible mass

 In the above reaction, proton is converted into neutron by emission of positron and a neutral particle of negligible mass called as neutrino, v. It cân be shown that if Z is the atomic number of daughter nucleus, the 1 difference in coulomb energies of mirror nuclei is equal to (6ze2 4TE0 5R where R is the radius of the daughter nucleus.

 This energy is spent by providing rest mass energy m.c? to produce a positron of mass me, imparting a kinetic energy Eg+ to B* particle and providing rest mass (m, - mp)c required for converting a neutron of larger mass, mi, to a proton of smaller mass, mp 6Ze2 5R + mc? + (m, - mp) c The experimental value of kinetic energy, E, imparted to B"-particles in the case of mirror nuclei can be used tó estimate R. The average value of R found by this method is (1.23 + 0.03) xA3 x 10 m. (ii) Mešonic X-rays The nuclear radius can also be estimated from the energies of X-rays emitted by mu-mesons which are called mesonic X-rays.

. The methods c field due mu? 4TEGR 2e x Ze Ze R = or Substituting the typiçal values for Z = 20, m = 6.64 x 1027 kg, e = 1.6 x 10-1 Coulomb and velocity v 10' m/s, R will be approximately equal to 1.5 x 10-14 elastic scattering of a-particles from nuclei with Z varying from 29 to 90 as equal to 1.35 XA X10- m. R was also estimated equal to (1.2±0.1) m.

 The average value of R has been estimated from the x 10- m from the life-time of radioactive alpha emitters obtained from Gamow's theory of a-decay by barrier penetration. The following typlcal methods have been generally 'used for an estimation of nuçlear radius, X A3 (i) Mirror Nuclei Method The mirror nuclei are pairs of nuclei which are obtained from each other by exchange of neutron with proton, e.g. H' He', 3Li' Be', C3, 19K 20Ca etc. A mirror nucleus like N is unstable and gets converted Into C3 by emitting B* (e*) and v as follows.

The Electrical Charge Distribution in a Number of Nuclei is not observed

 The Electrical Charge Distribution in a Number of nuclei is not observed

It had been inferred from the experimental observations that the majority of átomic nuclei are spherical or nearly spherical in shape. The electrical charge distribution in a númber of nuclei is not observed to be spherically symmetric which is indicated by their electric quadrupole moment. The radius, R, of various nuclei can be approximately given by R = RoA/3 where A is the number of nucleons and Ro a constant which is found k differènt: thods and lies in the range of (1.1-1.5) x 10-15 of measui nent of size are based either upon the effect of ele to distribution of electric charge in the nucleus when probed by electron or mu-meson, or the effect of nuclear forces which are sensitive to the distribution of nuclear matter in the nucleus when probed by nucleons or light nuclei.

 The size of the nucleus was earlier estimated from Rutherford's experiment başed on scattering of alpha particles by various atoms. It showed that larger is the angle of scattering through which a particles get scattered, closest įt approaches the atomic nucleus, A rough estimate of R can be made from the distance of closest approach of an alpha particle (2He') of charge 2e, mass m and velocity, v to, a nucleus of charge Ze.

If the kinetie energy is equal to the repulsive Coulomb energy between-these two particles, it comes to rest momentarily such that the distançe of closest approach R is given by m.

The Protons And Neutrons Constituting a Nucleus are called as Nucleons

 The Protons and Neutrons constituting a nucleus are called as nucleons

That Heisenberg proposed neutron-proton hypothesis of nuclear structure in 1932. It was then well established that the atomic nucleus consisted of the protons, each of mass 1.6726 x 10 kg and of positive charge of 1.6 x 10 9 Coulomb and neutrns of mass 1.6749 x 107 kg without any charge. The protons and neutrons constituting a nucleus äre called as nucleons: The fotal number of neutrons and protons gives máss number A and number of protons givės atomic humber Z of any nucleus which can be written as „X^ so that the number of neutróns, N, is ëqual to A- Z.

 It is well known that the nucleus is surrounded by a number of atomic electrons in various orbits each having a negative charge of 1.6 x-10 Coulomb. The total number of protons ina nucleus is, equar to the total number of orbital electrons in the orbit so that the atoms are electrically neutral.

 The protons and neutrons cơnstituting a nucleus are called as nucleons: The total number of neutrons and protons.gives máss number A and number of protons gives atomic number Z of any-nucleus which can be written as X^ so that the number of neutróns, N, is équal.to AZ.

 It is well known that the nucleus is surrounded by a number of atomic electrons in various orbits each having a negative charge of 1.6:x:10 Coulomb. The total number of protons in a nucleus is equal to the total number of orbital electrons in the orbit so that the atoms are electrically neutral. 10-12 kg and of positive charge of 1.6.x 10 º Coulomb and neutron.

Géneral Properties of Nuclei in Astronomy

 Géneral Properties of Nuclei in Astronomy

Constituents of Nucleus and Their Intrinsic Properties Rutherford's experiment on the scatterii falpha particles by mětallic foils was aimed at estimating the distancé of ciosest approach of än alpha particle nearest to the inner core of the atom, i.e. the atomic nucleus: It.was possible to estimate the size of an atòrmic nücleus from the Coulomb repulsive force berween an alpha pårticle of positive charge approaching the atomic core of positive charge when these' are separated by the shortest distance.

 It-was conclusivèly proved that the centrál core of an atom consists of a nucleus which is approximately spherieal in shape with rádius varying between and 10-13 em having a net positive charge.

 Prior to the discovery of neutron, proton-electron hypothesis was proposed on the basis of which the atomic nucleus wàs considered to Be composed of protons and electrons. It was assumed that electrons and protons were present within thě nucleus żXA which will have A protons and Z electrons pre-existing within the nucleus. 

It çould account for mass and charge of the nuçleus and explain B emission by nuclei but could not explain other properties: The electron-proton hypothesis of nuclear structure was rejected because it was contradictory to. the experimentally observed nuclear propeities.

 It was after the discovery of neutron by Chadwick as a pårticle with mass of about 1.67 × 1027 kg and equal to that of a proton but without any charge, that Heisenberg proposed neutron-proton hypothesis of nuclear structure in 1932. It was then well established that the atomic nucleus consisted of the protons, each of mass 1.6726 x 10 27 of mass L.6749 x 10 kg without any charge.

Intrinsic Properties Rutherford's experiment

Intrinsic Properties Rutherford's experiment

Constituents of Nucleus and Their Intrinsic Properties Rutherford's experiinent on the scattérii falpha particles by métallic foils wàs aimed at estimating the distance of closest approach of an alpha particle nearest to the inner core of the atom, i.e. the atomic nucleus: It.was possible to estimate the. size of an atomic nucleus from the Coulomb repulsive force between an alpha particle of positive charge approačhing the atomic core of positive charge when these' are separated by the shortest distance.

 It was conclusivèly proved that the central core of an atom consists of a nucleirs which is approximately spherical in shape with rádiuš varying between To 12 and 10 1 cm having a net positive charge. Prior to the discovery of neutron, proton-electron hypothesis was proposed on the basis of which the atohmic nucleus was considered to be composed of protons and electrons. was assumed that electrons and protòns were present within the nưcleus XA which will have A protons and Z electrons pre-existing within the nucleus.

 It çould, account for mass and charge of the nucleus and explain B emission by nuelel but could not explain other properties: The electron-proton hypothesis of nuclear structure was rejected because it was contradictory to the experimentally observed nuclear properties. It was after the discovery of neutron by Chadwick as a párticlé with mass of about 1.67 × 1027 kg nd equal to that of a proton but without any charge.

The slowly varying component of the solar radio radiation

 The slowly varying component of the solar radio radiation

The longer wavelengths from Sun that we receive on Earth originate in the corona where the characteristic temperature is high. The temperature relevant to the measured intensity of meter wavelengths is - 10° K. The intensity of this radiation undergoes slow variation, corresponding to the variations in the coronal structure. The measured radiation actually correspotids to a temperature of 10° K and a density nearly equel to three times the normal coronal density.

 The slowly varying component of the solar radio radiation thus fits with the concept that-it is thermal radiation trom regions of coronal condensations. The mechanism which gives risc to this radiation is free-free transition of clectrons in the hot coronal gas. The burst component of solar radio emission is sporadic, intense and nonthermal in character. This component is associated with the activity of the Sun. Different types of bursts have been recognized and the physics behind them is quite complex. As the name implies, bursts are manifested as the enhancement of. the radiosemission by onders of magnitude within periods as short as a few seconds.

 If the intensitaesof tursts are interpretedas of thermal origin, the corresponding equivalent blackbody temperatures would be of the order of 1012 K, which is absurd. The bursts are of different nature and they have been broadly classified into types 1, II, III. IV and V. Of these, all but the Type I bursts are correlated with flares.

 Type I bursts are not associated with flares or centres of activity. Type I bursts originate in noise storms that are produced high up in the corona usually above larger spots, their polarization showing no correlation with that o the spots. These bursts usually have lite-times of 0.1 to 0.2 seconds and during this period the wavelength of radiation remains fairly constant. The radiation.

 The theory of Gold and Hoyle thus predicts the release of the right amount of energy within the right amount of time as are observed in flares, through the meehanism of the magnetic field annihilation. The theory therefore implies the operation of a mechanism by which the twisted magnetic field which develops on the selar surface may become untwisted through flare discharge: Thistrunstormation irom twisted to untwisted field may have important bearing on the equilibriam configuration of the Sun. erg may be associated with such a twisted Soon after the production of radio frequency waves in the laboratory by Heinrich Hertz in 1888.

 Some scientists started thinking that the Sun might be a source of radie waves. Valuable work was one in this line by Wilsing. Scheiner, Nordmann, Jansky and others during the first few decades of this century and the end of the last century. But the actual detection of Sun.

The Second World War Independently By Stanley Hey of Britain

The second world war independently by Stanley Hey of Britain

  The shorter radio waves of wavelength - I cm come from the lower chromosphere which corresponds to a radiation temperature of 10 K. Meter and decameter wavelengths which are generated at the lower chromosphere are absorbed by ionized gas in the upper chromosphere and the corona, and therefore, cannot reach the Earth.

 The radio source was missed primarily due to poor technological advancement in those years. The discovery was finally made during the second world war independently by Stanley Hey of Britain, and by G.C. Southworth and G. Reber of the U.S.A. The subsequent decades were marked by intensive as well as extensive studies of the solar radio emission by scientists all over the world.

 The study of the radio-spectrum of the Sun has revealed that the radio emission from the Sun can be classified into two well-defined components: (a) a slowly varying component with sufficiently lone characteristic times, and (b) the sporadie burst component having much shorter characteristic times. The first component is of thermal origin and is recognized as the characteristic of the quiet Sun, while the second component is nonthermal which is characteristic of the disturbed Sun.

 As a hot body the Sun must emit radiations in rauio wavelengths, but since the temperature of the Sun is not uniquely defined (being different at different levels of the atmosphere) the nature of the solar thermal radio emission is altitude-dependent.

 The highly ionized corona is completely opaque to longer radio waves just as the case with the Earth's ionosphere. Thus, observing the Sun at different radio wavelengths means observing at different levels of its ätmosphere. This also enables us to distinguish between different levels in chromosphere and corona from which various disturbances give rise to radio emission.

Severny's theory has not emerged as fuli proof in magnetic field

Severny's theory has not emerged as fuli proof in magnetic field

 

 high gradient of fields. In fact, substantial modifications in the magnetic field structure are actually observed in the flare region after the flare has died out. Moreover, large magnetic field gradient is capable of accelerating particles to high energies which can subsequently emit radiation in wavelengths ranging from X-rays to long radio waves, as are actually observed in flares. But there are other observations of magnetic fields which Severny's cannot explain, and so Severny's theory has not emerged as fuli proof.

 A plausible theory of the origin of flares has also been proposed by Gold and Hoyle. Their theory relies for the energy source on coalescing and cancellation of two bundles of twisted magnetic lines of force. They imagine a filament consisting of a bundle of lines of force which emerges from a point in the photosphere and re-enters ät another point thus forming an arch.

 This bunch of lines of force may be twisted due to highly  In order that this energy may be released abruptly, a pair of such fil ments with initial magnetic fields in opposite directions but the same sense of twisting is hypothesized. Two such filaments placed close to each other will attract each other, interpenetrate, and a part of the field will be annihilated in a time-scale of the order of 10 seconds.convective motion in the subphotospheric layer.

 The energy density of this convective mass motion is 10 erg em only a few per cent of which is associated with flarë phenomena. The twisting of the field can greatly increase the intensit, of the initial moderate field. Calculation shows that an amount of magnetic energy equal to - 100 filament. This is the right amount of energy that is involved with flare phenomena.

The Earth's Ionosphere And Terrestrial Radio Communications

The Earth's ionosphere and terrestrial radio Communications

  The Earth's ionosphere and terrestrial radio communications are disrupted by flare X-rays. The solar ultraviolet radiation is greatly enhanced during solar flares. Sometimes, a single flare may outshine the entire Sun in ultraviolet radiation. Ultraviolet lines are generally enhanced but the L line remains remarkably unchanged during flares. It is interpreted that this line probably is radiated from the entire chromosphere. The Sun is the nearest source of cosmic rays. 

During large flares some of the solar (protons, eiectrons and heavier nuciei) are accelerated to very high energies-particles with energies even higher than 100 eV have been observed The highest flux of particles occurs, of course, in the MeV range. These high energy rays whose composition has been found not to differ significantly from the normal composition of the Sun itself. The most abundant particles are protons. Next comes the Alpha particles, and so on. The fraction of the flare energy contained in the flare cosmic ra s is, of course, quite small, usually less than one per cent. The particles are believed to be accelerated in regions of high magnetic field gradient but no entirely convincing explanation of the origin of solar cosmic rays has yet been established.

 Several theories have been proposed by various authors to explain the origin of solar flares. Flares have been speculated as manifestations of clectrical discharge. It has also been conjectured that flare energy might be produced by nuclear reactions in the surface layer of the Sun. Since both these theories have later been shown to be highly improbable, we shall particles are the solar cosmic not discuss these any further. Although none of the flare theories so far proposed appear completely satisfactory, we shafl briefly discuss two of the theories which can explain manyat the observed charactenstics of flares. Both these theories are based on the high magnetic Kelds in sunspot regions.

 Observationally, it is found that flares occur mostly in regions of complex spot groups, where magnetic fields are high. Magnetic fields of a few hundred gauss can supply energy of the order of a few times 10 erg cm, as flares are observed to possess (using E = B-18 TC). But the theory must also explain the extreme suddenness of the release of this energy. Severny proposed that flares originate as a result of magrnetic discharge near an X-type neutral point which may arise by interaction of fields of two neighbouring bimmagnetic spots in a complex spot group.

 The magnet field gradient is very high near neutral points. The intermetion of spot groups may initiate a kind of perturbation, which may trigger the magnetic discharge. thereby suddenly dissipating large amount of magnetic energy and neutralizing.

Particles leave the influence of solar gravity

 Particles leave the influence of solar gravity

 A vast range in size and brightness is observe  among flares and their importance is assigned accordingly. The importance is labelled 1, 2, 3 and 3 according as the areas covered by the flare lie in the ranges 100-250, 250-600, 600-1200 and 1200 respectively, which are measured inunts of a ailidntf part of the sotar disk. Besides the above classes, there are oflares iubelled with mporance and the microflares. Aithough the flare statistics partly depend on the observer, rough analysis indicate that about 80 per cent of flares are of importance I and about 3 per cent are of importance 3, while the remaining flares are of importance 2, the flares of importance 3" are of extremely rare occurrence. 

Flares, are events of frequent occurrence in the Sun and if we include subflares, there may be one flare every hour but flares of importance 3" hardly occur even once in a month. Flares are correlated with sunspot activity and the number of flares is observed to bear an approximate mathematical relation with the number of sunspots. It is found that the number.

Particles leave the influence of solar gravity and after a certain period depending on their speeds, impinge on the Earth's magnetosphere giving rise to geomagnetic storms and aurorae. This phenomenon, commonly known as solar wind, will be discussed in greater details in the Jast section of this Chapter. As we have already mentioned, solar flares are always accompanied by enhanced X-Tay and ultraviolet radiation.

 The first X-ray measurements during a flare were performed by H. Friedman in 1956 by sending rockets to heights in the range of 60 km. These data were extended by several other flights in subsequent years.

 Such measurements, in general, show two components of X-ray radiation: (a) a less energetic slow component lasting for a longer time; usually of order of an hour, and (b) a sudden short-lived high energetic component lasting for a few minutes. The first component originates from natural transitions in the coronal gas heated by flares to a temperature - 5 x 10 K. The second component is associated with bursts of nonthermal emission.

stares are the most energetic phenomena of highly transient nature

stares are the most energetic phenomena of highly transient nature

Stares are the most energetic phenomena of highly transient nature occurring in the Sun. While observing the Sun on spectroheliograms or filtergrams, sometimes the chromospheric emission lines, particularly the H and K Ca II lines originating in the sunspot and surrounding clage regions are observed to brighten up intensely within a few seconds or minutes.

 Such corcurrences are known as flares. The intensity of emission lines increases as much as four to five timies of those originating in plages within a few minutes, and sometimes within only 10 res. (for microflares). The strengths of lines then decay raher slowly within a time interval of 10 to 100 minutes.

 A very large flare can also be observed in the white light of the Sun when it appears as an intense bright spot against the continuous background of the spectrum of the surrounding solar disc. Flares are believed to originate in chromosphere but rise far up into the lower corona.

 They have a tendency to occur near the complex groups of spots and usually the occurrence is repeated many times in the same place. Occasionally, they are seen to occur when a spot group is rapidly developing. Some of these have also been observed to occur from the umbrae of large full-grown spots with complicated magnetic field structures.

 These observations clearly associate ilares with sunspot activity. Flares are classified according to their brightness and the areas covered by them. The area seems to be more important criterion of classification because usually, the larger the flare the brighter it is and with longer lifetime.

During his study of flare spectra with high dispersion instruments

 During his study of flare spectra with high dispersion instruments

Among other lines seen in emission are those of ionized metallic lines. the D, line of He I at  A and some H lines of the Paschen series. D, line in small flares is seen a absorption. Lines of Fe II and those of low excitation Fe I are strongly brightened in flares. All these observations are consistent with highe: excitation in flares. Electron densities in the range 10 to 105 cm and electron temperatures in the range   17,000 K have been suggested by various authors to be the most favourable state under which the observed spectra are produced.

 During his study of flare spectra with high dispersion instruments, Severny observed some fine structure granules which develop during the initial stage of the flares. These granules are short-lived with diameters - 400 km. Gas moves within granules with speeds as high  km snd it greatly influences the wings of lines of flare spectrum.

 Severny called these phenomena as "moastaches Moustaches are believed to be ditferent, fromU flares While flares are manifestations of release of large energies within a relatively short-time, moustaches are believed to be associated with small-explosion like events. Flares eject material with speeds ranging from a few hundred to as high as  km s. The streaming material perturbs prominences and filaments.

 The latter are sometimes destroyed or disrupted by flares, but strangely enough, reappear again after hours or days. Spectrographic studies indicate that large gaseous blobs which are manifestation of flare surges, rise high up into the solar atmosphere.

 Undergoing steady deceleration due to solar gravity and ome down into the Sun again with approximately the same speed. Besides this Sun-bound mass motion, flares also eject streams of corpuscular radiation in a wide range of energies. These high-speed.

Indicate that the rate of flare production associated with any particular

indicate that the rate of flare production associated with any particular

Flares per day of importance higher than or equal to I is - R/25, where R is the supe number given by (5.2). Thus, if R = 100 on any day, four flares of importance 21 can be expected. Since subflares are several times more numerous, if these are taken into acov a flare every hour will be more natural.

 Since flares originate almost always within abow 100,000 km of a spot group, the flare distribution on the solar disk bears close correspondenc with the distribution of spot groups. Further, quantitatively, observations indicate that the rate of flare production associated with any particular spot group depends on the area A of the spot group and on the time rate of change of the area dAldt.

 A typical flare has a surface area 5 x 10 cm (assuming radius = 4 x 10° cm and circular shape) and a height of -2 x 10° cm so that the typical volume is - 1029 cm. The total energy outpu' for such a flare is - 2 x 104 erg, so that the average energy density in a flare is - 2 x 10 erg cm. Most of this energy Is emitted in corpuscular radiation. Although flares radiate in most of the frequencies of the electromagnetic spectrum, from X-rays and rrays to long-wavelength radio waves, and also relativistic particles (cosmic rays), most of the energy is emitted in X-rays and ultraviolet radiation. The energy emitted in optical range is not too large, may be about 10 per cent and that in radio waves and cosmic rays is insignificant.

 Like size and intensity, the spectrum of flares also differ greatly from one another. In large flares the continuum is strongly brightened, but in normal flares of moderate importance the brightening of the continuum is not very marked, except over a region surrounding H H itself is observed in strong emission with large symmetrical emission wings.

 The wings, however, fade away quickly after the onset of the flare, while the flare may still linger. The central intensity of H becomes three to four times that of the continuum and the width may be as large as 15 Á.