Should Sex Education be Mandatory in High Schools Research Paper

Should Sex Education be Mandatory in High Schools - Research Paper ExampleFrom the news report it is clear thatdraws mixed reactions whenever it is brought up for discussion. Many are the tikes that emotions flare up between the conservatives and those who are of the alike. It is, however, necessary to state the facts about sex education in high schools and specifically, teenage sex as it is so that at the end of the day people makes an informed opinion on this matter. Sex education in high schools is something, which should be embraced because of the value that this topic creates among those children who undergo such trainings. It is necessary that the correct information be available for the childly minds so that they do non lose track as they try to experiment things on their own. It is common knowledge that the media nowadays have a lot of influence on the mindset of the teenagers.As the discussion stressesmost high school children are teenagers and they have access to the me dia, programs which portray sex as the best way out. There is a high level of influence also from the internet with sites that have pornographic materials and contents yet with no restrictions, meaning that these young children can access the same with a lot of ease. Denying the vulnerability of our children and refuting sex education a chance in high schools is like turning a blind eye to the young minds and leaving them in a state of confusion. The high school children are still young and with the correct information about sex, these children are likely to receive up into responsible individuals with good sexual behavior.

Denali National Park Essay Example | Topics and Well Written Essays - 1000 words

Denali National Park - Essay ExampleIt was renamed as Denali National Park and Preserve in 1980, when under National bet Land Conservation Act, another 4 million acres were added to it. It exemplifies interior Alaskas character as one of the worlds last groovy frontiers, its wilderness is largely unspoiled. (nps). It is an internationally acclaimed biosphere reserve under United Nations Man and the Biosphere Program. Wilderness value is an intrinsic part of this special KThe region is conspicuous by long cold weather followed by short growing seasons. The unpredictability of the weather condition, with unexpected snowfall, is another feature that makes it highly interesting biosphere.The climatic conditions of the set are mostly controlled by the Alaskan range. While the Gulf of Alaska brings in moisture and cold winds from the south, the mountain blocks it, resulting in drier and erratic climatic conditions to the Federal parts of the park. It is for these reasons, the south of the park has cool and pleasant summer and relatively warm winters as against the widely fluctuating temperature with long cold winters and short summers of the north. dampish foothill tundra comprises cottongrass (Eriophorum sp.) with dwarf shrubs, green alder (Alnus crispa) and dwarf birch (Betula nana). Drier tundra has mats of mountain avens (Dryas spp.), grasses and sedges. Above the alpine tundra, rock, snow and ice dominate (UNESCO).The geological aspect of the park is highly significant to study evolution of the species and understanding the complex ecological principles that are responsible for the extreme weather conditions and huge climate change of the new-fangled times. The park abounds with huge paleontologic resources like fossils of extinct species. The park is part of Morrison Formation Ecosystem which undertakes ecosystem studies. The evidenced of the presence of dinosaurs and other extinct species have made the park extremely popular amongst the students communi ty and public.

Extra 1 Essay Example | Topics and Well Written Essays - 500 words

Extra 1 - Essay ExampleApart from that they reflect the token era and time during which the manoeuvre took place. The scene designer designs the background of the bet with the colors that bring out, the right texture and desired mood to the audience.As the play unfolds Tartuffe succeeds in convincing Orgon to allow him to stay in his house indeterminately. He is opportunistic as he manipulates the allegianceaccorded to him by Orgon to manipulate him to his own advantage. He starts his schemes by pretending to be a staunch Christian and managed to fool Orgon to believing on every word he said (Steiner and Wilbur 35).Tartuffe tries to seduce Elmire, although she is frustrated by the foolishness of her husband, she does not give in to his advances. Unsuccessful he convincedOrgon to terminate the engagement of his daughter to a young man called Mariane whom she is madly in lie with with. The daughter refuses to get married to this hypocrite, but she is in a dilemma because she believe s that a daughter should obey her father (Steiner and Wilbur 55).The maid, who is convinced that Tartuffe is only after the familys fortune,makes sure that Valre and her lover are back together.In the play she is the only one who sees through Tartuffes malevolence right from the start. She turns out to be a very intelligent character in the play although ironically the maid is perceived to be a very insignificant job in the cabaret (Steiner and Wilbur 95).Paradoxically the church is misrepresented by the character of Tartuffe who turns out to be one of the main characters in the play. The actors try to bring out the theme of the play strongly by mastering the lyrics and context. Although they have the challenge of being inexperienced, they also manage to bring out the character traits of the key thespians.Conversely it can be observed that there is poor coordination between the actors, when they are in the stage

Guido Fubini Essay Example for Free

Guido Fubini EssayGuido Fubini, A famous mathematician, was born January 19th 1987 in Venice, Italy. His father, Lazzaro Fubini, was a mathematics teacher so he came from a mathematical background. Guido was influenced by his father towards mathematics when he was young. He attended secondary school in Venice where he showed that he was brilliant in mathematics. It was then clear that from this play he would follow this career.In 1896 Guido entered the Scuola Normale Superiore di Pisa. There he was taught by Dini and Bianchi, who quickly influenced Guido to undertake research in geometry. He presented his doctoral thesis Cliffords Parallelism in Elliptic Spaces in 1900. Most young doctoral students take a few years to make themselves well know in their area. However, Guido was lucky for his teacher Bianchi was about to publish an important work on differential geometry. Bianchi discussed the results of Guidos thesis in his treatise, which appeared in 1902.Guido remained at Pisa to qualify as a university teacher. Most mathematicians at this stage in their careers extend the work they have begun in their doctoral thesis, but not Guido. He attacked a completely new topic to the one he had studied for his doctoral thesis studying the theory of harmonic functions in spaces of constant curvature.Guidos interests were exceptionally wide moving from his early work on differential geometry towards analysis. In this area he work on differential equations, analytic functions, and functions of several complex variables. He taught courses on these analysis topics at two the Politecnico and the University in Turin. During World War I, Guido studied the accuracy of artillery. These investigations led him on to work on acoustics and electricity.Guido was forced to retire from his chair in Turin. He had no wish to leave Italy but he had two sons who were engineers and, always a man who was devoted to his family, Guido decided that his sons had no future in a orbit who se official policy was anti-Semitism. When he received an invitation from the Institute for Advanced Study in Princeton in 1939, Guidomade the decision which he believed was best for his family. They moved to the united States immediately, although Guido himself was in rather poor health by this time. Still, despite his health problem, he was able to teach for a few years in impertinent York. 5 years after moving to the United State Guido died of heart Problems on June 6th 1943.

Plot Summary Essay Example for Free

Plot Summary EssayThe put-on is dictated in the Dublin slums or tenements in the years of the Iris Civil War 1922 and 1923. The whole play centers on the Boyle family. Juno Boyle is married to Boyle who calls himself Captain Boyle. Boyle is a useless and positive drunkard who shuns the humans of work at every stage in the play, and spends his time in the pub drinking with his friend Joxer Daly. The Boyles live with two children maverick and bloody shame. Johnny is a sickly individual who has been involved in the Republican movement simply he ended up betraying a comrade by the name of Tancred. Johnny spends his days locked up in the admit fearful of his life. His mother Juno is a selfless character who is concerned all the time virtually other people. Junos daughter bloody shame is deeply concerned al just about appearances. She is a shallow character who seems to judge people and things from the outside. When we meet her at the offset printing of the play, we learn she is on strike because of the dismissal of a young girl called Jenny Claffey. Yet we atomic number 18 told from Juno how Mary never had a good al-Quran to say about Jenny Claffey in her whole life. The family are told that they will inherit money from a distant relative who has died.Bentham is the solicitor who informs them of this fact. He begins to have a relationship with Mary and she becomes pregnant. Bentham shortly after this abandons her. The Boyles begin to borrow money and accumulate a great deal of debts. The legacy never existentizes, and the Boyles are forced to return the borrowed goods. Johnny is dragged off to be shot for the betrayal of Tancred. Juno finally realizes that Boyle will never take on his responsibilities as father and breadwinner and so she leaves him and sets up home with Mary. Themes/Issues Poverty This theme dominates the play at every level.The whole play highlights the cruel irony that while many people were rubbish for ideals and principles ther e were others who were suffering from the debilitating effects of the poverty. Because of the negative effects generated by poverty escapism assumes a major and dramatic element in the lives of characters. Marys tragic situation occurs because of poverty. When it becomes clear that the Boyles will not inherit any legacy, Bentham disappears forever abandoning Mary alone to have her baby. Jerry Devine standards of what are essential features in a husband are set out in terms of money. At one stage he tells Mary how the hire out is worth 3 50.Juno who is the only character rooted in the harsh practical everyday world of necessity realizes that money, hard work, and responsible social commitment are stronger and more(prenominal) realistic values in this world than principles and ideals. Her pragmatic stance on how principles wont pay butchers is in striking contrast to the incessant turning away from reality inherent in all of the other characters. Religion The theme of Religion is a lso a dominant feature in the play. The play is set against a strong Catholic background. O Casey makes frequent use of images of Our Lady and the votive light to project an air of realism and authenticity in the play.thither are also a variety of different religions, and attitudes expressed throughout the play. One of O Caseys chief mottos in the play seems to show the co- cosmos of strong religious convictions, together with a sincere and humane commitment to ones fellowman. Junos faith is sincere, authentic, and traditional. She believes on Johnnys closing that God can do nothing against the stupidity of men, that her husband should be praying novenas for a job, and that what Ireland needs is more piety. On the other hand, Bentham espouses a religion by the name of Theosophy.This is projected as vague and abstract and certainly seems to be compatible with his own shallow commitment to people. Reality and Fantasy The play dramatizes the encroach between the dream world and the world of reality and shows what happens when a character is stripped of his illusions and forced to face reality. Boyle the poseur or Paycock struts throughout the world of the play on a false and imaginary sense of his own self- importance. His whole life and career consist in fabricating dreams of his gallant years as a superior fighting heroic feats and sailing the oceans of the world.The news of the legacy provides another outlet to Boyles habitual evasion of reality, he sees himself as a potential investor on the Stock Exchange. His whole life is a lie. His pains, which are invented for the sake of shirking and avoiding work, become real to him. His refuses to face up to the truth and reality about Bentham and the pretence surrounding the news of the will. When reality invades at the conclusion of the play in the form of Marys pregnancy and the actual removal of his material possessions, Boyle is unable to cope. His final entrance dramatized in a drunk fragmentary soliloquy is tragic.His habitual ladder into fantasy is pathetically expressed through his drunken pose Commandant Kelly died. in them arms.. Tell me Volunteer Bullies says he that I died for Ireland. Mary who represents the younger generation also falls victim to illusion. On her first appearance in the play, she is shown to be on strike for a principle. The oppressive and stifling atmosphere generated by the tenement life forces her to seek escape through Bentham. For her he represents another way of life and values outside the restricting and debilitating atmosphere within the two- roomed tenement.She falls victim to the subtle deception of Bentham middle-class gentility. She is blinded by external appearances and ends up a tragic victim of Benthams hypocrisy and selfishness At the conclusion of the play, she is forced to return to the reality of the slum life with Juno in spite of all her attempts to escape through learning and books. Answer Juno and the Paycock is a play that was wri tten by Sean OCasey. It is one of the most often performed and highly regarded plays in Ireland. Juno and the Paycock was first staged at the Abbey Theatre, Dublin in 1924. Juno and the Paycock Tragoi-comedy.Tragi-comedy is a kind of writing in which comedy is hovering on the brinks of tragedy. OCaseys Juno and the Paycock is a tragi-comedy although, on the whole, it is a serious and somber play having much destruction and violence. But there are a number of comic elements in the play which would not fit into the pattern of a tragedy. On the other hand, as the comic elements do not outweigh the tragic ones, it would be inappropriate to label the play as a comedy. It means there is a co-existence in the play of tragic and comic elements and so, the best course is to treat it as a tragi-comedy. hatful Union. JUNO AND THE PAYCOCK Sean O Casey round 1 (in a labour family house, not very well furnished) Johnny and Mary Boyle are siblings and members of a Trade Union. Mary is 22 and Joh nny is her younger brother. He was injured at the hip by a bullet and at the arm by a bomb he is an activist. One of Marys friend, Jennie Claffey has been fired so Mary wants to demonstrate (Union Trade). Mrs Boyle doesnt support those behaviours on the part of her Children. Mrs Tancred son was killed during a an armed fight. The Boyle family is poor and Mrs Boyle borrows money.She doesnt want her husband to come at home with his friend, Joxer, and to spoil all the coal and the food. Johnny is crippled and relies much on others. Jerry Devine has found a Job for the Captain (Junos Husband), but the latter pretends the pain is his legs prevents him from working. Jerry Devine is in Love with Mary, but she hangs out with another guy. Jerry Devine saw them together. Jerry devine is a very polite and a very correct guy. Juno makes Joxer go and goes to work. and so Joxer comes again. He is much afraid of Juno. He and the Captain have a conversation. The captain doesnt want to work.He does nt like clergymen. Then Joxer has a quick leave as Juno comes back with Mary and Mr Bentham (the other guy Mary sees). He is 25 and seems to be rich. He has great news for the captain. Benthan says Ellison of Santry, a relative of John Boyle the captain) is dead and he will receive half of his keeping. Then John Boyle get angry with Jox. Things now goes well between he and his wife though. ACT 2 (two days later + the pace is full of belongings and adornments of all sorts) Boyle is friend again with Jox and spend is money joyfully. As he is rich, he seem to have changed views about clergyman.Father Farell (the one proposing him the job in particular). Charles and Mary seem to appreciate each other much. Boyle and the former are having a conversation. As Bentham speaks about spirits Johnny sees the phantom of Robbie Tancred in the leave room. The captain is sometimes called Jack. Mrs madigan (a woman to whom the captain owes a few pounds) comes in. They sing. Then Mrs Tancred is hea rd in the street, going to the burial of her son. Nugent (tailor + he talked with the captain about his job and the Father) comes and asks them to shut the gramophone down. They all go out except John, to see the burial procession.The mobilizer comes and asks John to take part in a meeting of the militia. ACT 3 (two months later+ same setting) Bentham hasnt been seen for a month. He has given up on Mary. Mrs Boyle brings her to the doctors. The captain has borrowed much money to all his neighbours but it seems he wont get it. Nugent, the tailor comes and takes back a suit he had made for Jack. Mrs Madigan, who wants to be re paid, comes and takes the gramophone for which the captain hasnt paid yet. The captain and Joxer quarrel about the rumours and the girls come back from the doctrors. Marry is pregnant, Bentham is the father.Bentham also misinterpreted the will and the Captain wont have his share. People come to back away the furniture that hasnt been paid for. Two irregulars (f rom the militia) take hold of Johnny (called Sean) to take him by force. He is accused of having killed Tancred. One hour later the house is completely empty. Johnny was killed. Two policemen come for Mrs Boyle to check up the corpse. The girls will live together and take care of the baby. Until Mary drops they will live at Junos sister. Joxer and Boyle come back completely drunk. Boyle says the whole world is in a state of crisis.

The heat energy given out Essay Example for Free

The light faculty given out EssayI think it willing happen for the following scientific reasons As the size of the century copy chain grows, more than bonds atomic number 18 added to the structure of the inebriant. This means that each time, more energy from the surroundings must be extracted in rate to break these off rotary bonds ( energy-absorbing stage). Yet, the more energy that is taken to break the bonds, the more energy is delectationd to form the products bonds and this makes the energy of the products greater than that of the reactants. The alcohols start off with methanol, which has 0 carbon carbon bonds, 3 carbon hydrogen bonds, 1 carbon oxygen bond and 1 oxygen hydrogen bond.When the products are formed, excess energy is released which is mainly out-of-pocket to the amount of C = O bonds being made. The products of methanol work 2 C = O bonds and 4 O H bonds. Since a C = O bond has a high energy value of 805, many of them will ensure that the energ y of the products is greater than that of the reactants. Here are the theoretical values for the input, rig and exothermic genus Oestrus energy of methanol along with a diagram and the bond energy values constipate type Energy Value (Kj) Bond type Energy Value.Now lets take ethanol as an example. The bonds are 1 C C bond, 5 C H bonds, 1 C O bond and 1 O H bond. The number of C H bonds has risen by 2 and the carbon bond has gone up by one. For the products, there are 4 C = O bonds and 6 O H bonds which is two more bonds than methanol. Here is the input and output enumeration for ethanol The theoretical input energy for the ethanol is greater than that of methanol as is the output energy and the exothermic heat energy difference. The same is shown with proponal, butanol, pentanol, heptanol and octanol.The material body that we see is that when the alcohols gain a carbon, they have to break an extra 2 C H bonds (and C C bonds if it is connected to another carbon) and this makes it need more energy from the surroundings which comes out as more energy when the products are formed. The theoretical values show that the more bonds in the reactants, the greater the bonds in the products and the more the theoretical energy difference. Also, since there is a regular change in the structure of the alcohols, then there is probably a regular change in the energies too.There is a regular change in the exothermic energy given out. Here is a graph of my theoretical values in order to show the relationship between the energy given out and the number of carbons The number and range of results I will need, to obtain reliable evidence are I will need to have at least 20 results twice for each different alcohol, perhaps thrice if possible. If each experiment is make at least once, then averages of mass differences can be obtained and will make the energy given out by one mole of alcohol readings of each, much more accurate.The range of these results will be from the a lcohol ethanol to the alcohol octanol which is 7 alcohols in solely as we are excluding methanol and heptanol. This will enable me to make bond energy charts for each alcohol to easily identify and illustrate the relative heat energies released. I will require the appliance for my investigation Spirit burners of each alcohol, 5 heatproof mats, metal stand and clamp, thermometer, can, ruler, measuring cylinder, splint and a cardboard can lid. The way I will use this apparatus to obtain reliable evidence is shown belowOnce the apparatus has been assembled as shown, fill the measuring cylinder with a specific volume of water supply and pour into the can. The starting temperature of the water should be recorded and the temperature it will go up to should be calculated by adding the original temperature to a temperature rise (e. g. 20i C + 7i C =27i C). Check that the distance between the alcohol and spirit burner and that the temperature rise is the same for every experiment. Weigh t he alcohol before the experiment and then give in the shelter of the windbreakers, so it is directly underneath the can.Light the alcohol using a lighted splint and close it in with another heatproof mat. guard glasses must be worn as the alcohols are flammable and if some gets on your hands, they must be washed immediately in sheath any flame touches your hand. Also, it would be safer and less of an equipment hazard if one Bunsen burner were used. Put the cardboard lid on top of the can and the thermometer through it (punch mending in lid and slide thermometer through). After the water temperature goes up to the one decided, put out the alcohol and weigh its finishing mass.This should be recorded. To prepare for a repeat empty out the can and refill and change the alcohol with another of the same type. Repeat the procedure for other alcohols and take average. I have used the following to help me plan my investigation I have used the following books to help me plan my investiga tion Physics for you by Keith Johnson. On page 37 to 39, I found out information concerning measuring heat energy, its values, specific heat capacity and a table displaying specific heat capacities of different substances.Revision guide for GCSE Double Science Physics where on page 67 to 68, there is information about heat transfer, evaporation, the conduction of heat and vibrating particles. Chemistry for you by Lawrie Ryan (Revised National Curriculum Edition). On page 178 to 179, there is information regarding organic molecules such as alcohol their structures, physical properties and homologous series. On page 182, there is information on the combustion of alcohols, a brief explanation of the combustion experiment and combustion formulas.On page 186, which is about energy transfer, there is more detailed coverage of incomplete/complete combustion and fuels. On page 190 to 195, there are things about exothermic/ decalescent reactions, what happens to the temperature during these reactions, energy level diagrams, making and breaking bonds and finally bond energy calculations. Nuffield Book of Data sheet has exothermic heat energies of all the alcohols combustion reactions and all the varied bond energy values.I have done the following experiments to help plan my investigation periment on page 191 to see what substances have endothermic or exothermic reactions. Previous practise experiment of the alcohol investigation, which helped me to find corrections for certain procedures, various precautions, tips that would produce less inaccuracy, discover key factors and how to set up the apparatus. Here is the set up of my results table as an example of what I learnt from the practise experiment.

Principles of the Photoacoustic Effect

Principles of the Photoacoustical Effectphotothermal and photoacousticPhotothermam science encompasses a wide range of techniques and phenomena based upon the conversion of clothed optical vigor into heat. Optical energy is preoccupied and eventually converted into thermal energy by an enormous number of material solids, liquids, and gases. In fact, the optical energy is absorbed, the excited states in atoms or molecules lose their excition energy by a series of non- radiative transitions that provide in a general modify in the material.The underlying principles of the photoacoustic take have been study for more then a century. it was named photocoustic because the photothermal heating take was detected by an in condition acoustic method in 1880. Alexander Grshsm Bell (cited in Favier J.P.1997) had discover the early concept of the photoacoustic effect when he tried to explain the operation of his photophone. He had done a lot of experiments on photoacoustic effect with soli ds, gases and liquids, where modulated debile was used to illuminate the sample. through the experiments, Bell discovered that when a periodically interrupted beam of sun animated shines on a solid in an envelop mobile phone, an audible sound could be heard by means of hearing tube attached to the cell. the photoacoustic effect discovered by Bell was regarded as a part of the family of photothermal phenomena encompassing many effect produced by the heat generated in a sample due to the assiduousness of electromagnetic energy.In 1881,both Tyndah and Withem Roentgen (cited in Favier J.P. 1997) confirmed Bells experiment on gases. they found that an acoustic head could also be produced when a gas in an enclosed cell is illuminated with transition light. But due to the limitation of hearing tubes as detectors in the early experiment, progress in the field of photoacoustic died down. therefore, the photoacoustic technique had lay dormant for almost 50 years, until the advent of a mi crophone 50 years later the photoacoustic effect with gases was reexamined. then it had become a well-established technique for gas synopsis. photons in the photoacoustic cell absorbed by the gas was converted into kinetic energy of the gas molecules, thus it gives rise to nip fluctuations within the cell.All the discoveries in the photoacoustic effect originate from 1938 was totally limited to gases only. the phoyoacoustic effect on solid matter did not occur until the early of 1970. it is almost 90 years after Bells discovery, since 1973, photoacoustic effect has strongly reemerged on the solid sample. ti has revived with the development of a very useful technique spectroscopic investigation of solid material.The photoacoustic effect in condensed matter whitethorn be detected by microphone absorption of modulated light by a solid sample produce a modulated heating of the sample surface. This heating cause pressure waves to be created in a gas in contact with the sample, produci ng an acoustic signal in the gas, which may be detected by a microphone. the sample, coupling gas, and the microphone are enclosed in a gas light photoacoustic cell. the cell acoustically isolates the microphone from external noise and contains a window enabling the modulated light to illuminate the sample (Almond and Patel 1996)Bells first experiment on a condensed matter sample, revealed the fact that the loudest signal were produced by sample with the darkest colours. a few other experiments were performed in the years following, however condensed matter photoacoustic died out until the 1970 Parker (1073) carried out the experiment about to measure the phootoacoustic effect in solid when he tried to carry out the experiment on the photoacoustic effect in gases. in his experiment, he worked on gas strain photoacoustic, attributed an anomalously large PA signal to absorption of light by the windows of his cell.Three years later, Rosencwing and Gersho (1976) derived the one-dimens ional theory for a photoacoustic effect from asolid material, which has become know as the R-G theory and which has basis for the most other theories on microphone photoacoustic detection from a solid sample. in his hypothesis, the primary showtime of the photoacoustic signal result from a periodic heat flow from the solid to the surrounding gas. these can be explained when the beam of light falls onto sample, the heat produced by the light absorbed in the sample will diffuse from the sample to the gas through the sample gas interface. by modulating the light beam, we are actually causes the expansions of the gas point which near to the sample and this will finally create a sound wave.The R-G theory has been shown to be agood model by subsequent experiment work. Therefore, it led to direct expansions in photoacoustic research in 1970. The publication of the R-G theory, stimulated work in photoacoutic and number of papers have been written on the subject, describing various light s ources, sample, cells, inflexion technique and frequencies, detection methods and signal processing apparatus. This theory will be discussed in detail in the next chapterThe photothermal and photoacoustic research was investigated since 1970 due to three major factors.i) Devlopment of intense light sources, such(prenominal) as laser and high pressurearc lamps,such as xenon arc lamps.ii) Development of sensitive detection equipment, such as condenser and electret microphones and piezoelectric detectorsiii) Development of more sensitive signal processing equipment such as filters and sensitive lock -in amplifiers.The improvement in the preceding(prenominal) three areas enabled the photoacoustic effect to be studied and hence higher sensitivity photoacoustic spectroscopy could be performed.Schemes of Photoacoustic Detection.All photothermal system employ a modulated source of electromagnetic radiation usually a light source, to generate modulated heating in a sample medium. the syst em rely on the absorption by the medium of electromagnetic energy and its subsequent conversion into thermal energy. this heating result in a number of physical spays inand around the sample, figure 1.1 is schematic illustration of the phenomena resulting from the exposure of sample surface to a localized periodically modulated light source.in addition to a change in the temperature of the sample, it is also produced infrared, acoustic waves, surface expansion, thermoelastic waves, surface reflectivity modulation and refractive index gradient in the medium in contact with the heated surface. all of these effects could be used to probe the photothermal response of an enormous number of materials solids, liquids, and gases. the thermal wave detection method were classified in to acoustic and thermal detection techniques. acoustic detection technique employ either a gas condenser microphone for the detection of pressure variation in air or a piezoelectric transducer for the detectio n of thermoelastic waves in solid media. thermal detection method includes the use of thermocoupe or pyroelectric transducers (photopyroelectric detection, PPE)to detect waves directly. (Murphy et al. 1992) calamity Refractive index gradient Infrared emission Surface Reflectivity modulation Acoustic waves Surface expansionthermal thermoelasticwaves wavessamplefigure 1.1 photothremal effect caused by illumination of a surface by a modulated beam of light (Almond and Patel 1997)1.3 Objective of the present study.CHAPTER 2THEORY2.1 Introduction.In this chapter, will discuss the theory of photoacoustic effect in the condensed matter.the formulation of Rosencwaing -Gersho (R-G)theory from the acoustic detection technique employ a gas condenser microphone for the detection of pressure variation in air are described. According to R-G model,when heat is created by means of non radiative transition with a boundary layer of the gas in the cell. Since the light is chopped, the photoacoustic s ignal is generated due to an acoustic pressure disturbance at the sample -gas interface transferred from the gas medium to the microphone.2.2 Rosencwaing -Gersho TheoryThe Rosencwaing -Gersho theory, known as R-G theory, is an one -dimensional analysis of the production of a photoacoustic (PA) signal in a simple cylindrical cell resulting from the absorbed light energy. The model is schematically shown in figure 2.1 from the figure, the photoacoustic cell has a diameter D and length L. It is assumed that the length L is small compare to the wavelength of the acoustic waves and the microphone detecte the average pressure produced in the cell. In the present case, they also assumed that the light is not absorbed by the gas and backing material. The sample has thickness and diameter D. The sample is mount so that its front surface is expose to the gas (air)within the cell and back surface is against a backing material of thickness . the length. . Of the gas volume is minded(p) by.=Wh en a sinusoidally chopped monochromatic high passing through are window of the cell and incident upon the solid sample, the intensity I at the depth x is given by