Monday, January 27, 2020
Scientific Concept of Magnetism
Scientific Concept of Magnetism There are two essential requirements for generating a magnetic field which are magnetic material and current. The magnetic field is a region in which the magnetic effect due to electric current or of a magnet is precipitated. When small magnet is brought in the vicinity then torque will be experienced on the test magnet up to this magnet becomes oriented in a particular direction. The magnitude of this torque is nothing but measurement of the strength of the magnetic field and the shown direction of orientation which is the direction of the field. Magnetism means it is a physical phenomenon involving magnetic fields and whose effects upon materials. The magnetic fields may be set by electric currents or by magnets. In the magnetic material, the individual atoms cause magnetic fields when whose electrons have a net magnetic moment due to their angular momentum. Due to angular momentum of charged particle a magnetic moment arises whose cooperative effect acquires the macroscopic magnetic field of a permanent magnet. Hence only one kind of magnetism was known until 1821which was produced by iron magnets. It was proved that when an electric current flows in a wire then needle of compass moves nearby it. This new phenomenon was studied by Ampere, concluded that the nature of magnetism which was quite different from basically a force between electric currents. The two parallel currents which are in the same direction attract each other and on the other hand, the two parallel currents in opposite direction repel each other. According to the modern theory, magnetism in solids arises due to spins and orbital motion of electrons and also due to the spin of the nuclei of an atom. Due to motion of electrons, the magnetic effects produced in magnetic materials. The magnetic moments associated with the atoms are due to three types of motions which are, one is the electron orbital motion, second is the change in orbital motion caused by an external magnetic field and third one is the spin of the electrons. In most of the atoms the electrons occur in pairs. When electron pair spins in opposite directions then they cancel each other means there is no net magnetic fields exist. In magnetic materials with some unpaired electrons show a net magnetic field and which react more to an external field. The major contribution is due to spin of unpaired valance electrons in magnetic field of the magnetic materials. These unpaired valence electrons produce permanent electronic magnetic moments. The nature of magnetization produced depends on presence of the number of unpaired valence electrons in the atoms of the solid and on the relative orientations of the neighboring magne tic moments. For the generation of net non-zero magnetic moment, number of such magnetic dipoles may align parallel to each other, with or without the application of magnetic field. As a magnetic material is kept in a magnetic field then it becomes magnetized. It means that the material itself becomes a magnet. Hence the intensity of the induced magnetism is called the magnetization. The magnetization is also called as the magnetic moment per unit volume of the material. The magnetic force anywhere in space of magnetic field is described by a vector field .It is also called the magnetic induction. Let H Magnetic field M Intensity of magnetization B Magnetic induction Then the magnetic induction B is given by, B =  µ0 (H+M) Where  µ0 is the permeability of free space. The magnetic field produces due to motion of an electric charge. The electrons in a bar magnet about atomic nuclei are in constant motion. The motion of charge creates a tiny current, hence produces a magnetic field that means every spinning electron is a tiny magnet. When two electrons which are spinning in the same direction creates a stronger magnetic field. When a pair of electrons is spinning in opposite direction then their net effect cancel each other, hence there is no magnetic field which occurs in substances such as rubber, wood and plastics etc. When magnetic field is applied then materials turn magnetic field, they acquire a nonzero magnetization. On the basis of magnetic property as per the application of an external field, magnetic materials are divided into temporary and permanent magnets. In case of temporary magnets after the removal of the applied field will lose whose all or most of their magnetic properties. On the other hand in permanent magnet magnetic propertie s will retain or keep for a very long time. These temporary magnets are made from the materials such as iron, nickel and cobalt. Hence, these materials are called as soft magnetic materials that mean outside a strong magnetic field they usually do not retain their magnetism. The total energy of the crystal is determined by the distribution of cations in a given spinel oxide. This parameter depends on other factors such as the size of ions, the limited space between the repulsive forces , Coulomb interactions between charges of these ions, effects of polarisation and ordering of cations. With the help of spontaneous magnetization Ferromagnets are characterized. In the absence of field, ferromagnets attain saturation magnetization in each of the domains. But the magnetization curve shows that an unmagnetized ferromagnetic sample displays no overall magnetization in zero fields. However, it requires an appreciable field to produce saturation magnetization value. Weiss domain hypothesis explained this discrepancy in between the theory and the observation. According to Weiss domain hypothesis, a ferromagnet of macroscopic size consists numerous regions is known as magnetic domains in the demagnetized state. In each domain all the atomic moments are aligned in same easy direction. In orders to minimize the magneto static energy, the direction of the spontaneous magnetization varies from domain to domain. The multi domains are formed, if the ferromagnetic grains are subdivided into many domains with walls between them. When the grain size which is in the order of the wall thickness, hence it is a single domain grain. The difference between multi domain and single domain grain is that the multi domain grains possesses a net zero magnetic moment due to different directions of the individual domain magnetization, but the single domain grains are always show the saturation intensity below its curie temperature. The single domain size range would be from less than 1OOOA ° which is less than the lattice constant of the material and hence these grains are also called as fine particles. The hysteresis behavior of these particles shows reversible magnetization curves. In this case there is a zero value of the remenance and the coercive force. The multi domain particles require a much larger magnetic field than single domain particle and hence super paramagnetic particles acquire saturated magnetization. When the changes in appropriate temperature, the hysteresis loop of single domain and due to super paramagnetic particles are interchangeable. However the m ulti domain particles are independent of temperature. In magnetism the major contribution comes from the spin of unpaired valance electrons which produces permanent electronic magnetic moments.
Sunday, January 19, 2020
Education of Philosophies Essay
After reading through the different philosophies of education, I have come to the conclusion that I can relate to the student centered philosophy the most for several different reasons. As stated in the chapter, education is not a competition. I don’t agree with having students take multiple choice tests to see who gets the highest amount of right answers. Many students suffer from test anxiety and giving them one chance to prove they are educated on the subject isn’t fair. I am a firm believer that students don’t gain knowledge from textbooks, they gain knowledge by being out in the real world. To me, experiencing things first hand is the strongest way to learn about a subject matter. This leads me to the progressivism philosophy of education. I am all for experimental learning, having students have the chance to learn by doing. Another method of this is called the scientific method. This happens by expecting students to pursue their answers through problem solving and critical thinking, and are rarely expected to find their answers in a textbook. Another method I agree with is social reconstruction. Democracy in a classroom encourages teachers to guide an important dialogue among the children, but to avoid telling students how to think or what to believe. Social purpose gives students an opportunity to instill habits or values that are useful to the greater community. I believe students should be encouraged to think about local, national, and international issues in the real world. More importantly, I believe existentialism is the most crucial student centered philosophy in education. Giving students the ability to develop their own creativity and different ways of self-expression is something that should be focused on in every school. Students should be allowed freedom to go at their own pace and should be inspired by the things shared among peers in the classroom. Students are expected to be in control of their own lives at school while playing an active role in functioning community, students should leave the school with the important ability to think critically.
Saturday, January 11, 2020
Poverty In United States Essay
United States of America being among   the richest and most developed nations one would expect poverty to be a vocabulary that only exist in the national policies of third world countries.            By comparison Americans can be described as wealthy but there are some pockets of poverty in this vast and rich nation This paper attempts to explore poverty situation in United States highlighting its causes and characteristics, digging deeper to understand which group of people consist the poor.            A report released in 2002 shows that there were 35 million poor Americans, this represented roughly 10% of the population, and this figure has been rising Presently 12% of Americans are living below the poverty line.            By definition poverty is described as that condition where one is unable to meet the basic need in life, that’s one, can not afford a well balanced meal, decent housing and clothing. Poverty in United States is somehow different from the one experienced in least developed nations where living on less than a dollar qualifies one as poor. The poor in America constitute people who depend on state welfare since they are unable to provide for themselves, every year people fall in and out of poverty.  In a period of 10 years 40% of American fall in and out of poverty, this is attributed to fall of their income, when one of the family member moves out, among other situations (Fisher, G.M., 2003)            Some groups of people are more prone to poverty than others. This depends on their economic social or cultural position they occupy in the society. There are those who are unemployed meaning they do not engage in any income generating activity. Crime on one hand is a result of poverty or it can breed poverty. Poor tend to engage into criminal activity or they are driven into it by poverty. Apprehended criminals in correction centers rarely engage in economic activity while victims of crime e.g. thefts have to replace the stolen property eating on their savings. (Zweig, Michael, 2004)            Households headed by women on average tend to be poor in comparison to those with both spouses. In this type of a family woman is the sole bread winner. Most of her income goes towards provision of basic needs with less or no savings therefore making it difficult for this family to rise beyond poverty line (Martin N.,2008).            The size of the family affects family income, large families have more mouths to feed, more household bills to clear, huge spending in insurance, education and healthcare. If this type of family income is not enough they will for ever be trapped in poverty cycle.            Other groups that are likely to be poor are the unskilled, the less educated substance abusers immigrants and children.            Causes of poverty in America are several they range from economical, cultural, and geographical to social. . Distribution of resources largely affects people ability to produce. This also determines employment opportunities available which by and large dictates people incomes. States endowed with resources will have low poverty rates than those with little or unexploited resources. (Adams, J.Q, Pearlie S.A, 2001)            Economic condition which is not favorable will result to increased poverty rate, recessions leads to rise in inflation which means people pay more for the same goods they were buying but their income remains constant, and this means savings are curtailed. For example recession in 1982 led to rise in poverty rates from 12% to 15%             Education equips Americans with skills that enable them to gain employment or venture into business. On average Americans with a college diploma have access to high paying jobs compared to the less educated. To a greater extent educational level determine ones income, less educated are likely to earn less making it impossible for them to afford a decent living. On the same line education level dictates opportunities available to an individual. Unskilled labor attracts low pay making unskilled laborers more prone to poverty than their skilled counterparts.            Rural and urban settings provide greater disparities as far as living standards are concerned. Americans living in urban areas have higher incomes when compared to their rural countrymen. There are more opportunities in urban areas due to high population with disposable income and better infrastructure. In rural areas opportunities are few and are limited to primary production e.g. agriculture, mining e.t.c.This means income generation activities and employment opportunities are fewer and only attract the less skilled            Regionally, most of the southern states have higher poverty rates especially the rural areas .This is due to few employment opportunities and historical background.            Children are more prone to be poor than any other age group. According to the information released from population survey by census bureau in 2004, 21% 0f children were considered as poor. A greater disparity is seen when it comes to racial lines, almost half of African Americans and 40% of Latino kids are trapped in poverty circles. (Harrington, M.,1962).            Immigrants are great victims of poverty .Those with low education earn their living in low paying jobs. Illegal immigrants are even more disadvantaged as they can not gain any meaningful employment, therefore remaining in poverty circles for a long time            In conclusion, poverty in United States is dynamic, one may be in and out of poverty throughout their lives. Though there are conflicts as to who is poor, there is a common understanding that those who live on an income that is below what an average American earn is living below poverty . What constitutes poverty in United States may be middle class in some parts of the world especially in least developed nations. Poverty is a limiting factor in the society as it denies some Americans decent lives curtailing their freedom to enjoy lives. Policies need to be implemented to lower the poverty rates so as to rid United States of poverty. Reference Adams, J.Q.; Pearlie Strother-Adams, 2001. Dealing with Diversity. Chicago, IL: Kendall/Hunt Publishing Company. . Harrington, Michael ,1962 The Other America. Macmillan. Fisher, G.M. ,2003 The Development of the Orshansky Poverty Thresholds. Macmillan Zweig, Michael ,2004 What’s Class Got to do With It, American Society in the Twenty-first Century. ILR Press. Martin N. ,2008. Social Inequality: Patterns and Processes, 4th ed.. Boston: McGraw-Hill
Friday, January 3, 2020
Physics Of The Physics Classroom - 944 Words
If you picture a group of high school seniors blankly staring at a smartboard, fighting off sleep, despite the fact it was the last class of the day, that was my physics classroom. I was one of a small group that sat near the front of the classroom and made an earnest effort to learn something each day. The class had a set routine: lecture, set of worksheets, one day of review for the test, and then the unit test. Our teacher was always extremely helpful during the work time given for the paper assignments, and would bring around props that related to the unit, but students would not take advantage of the time, because there was much leniency with due dates and even the test date. I can learn in circumstances like that physics classroom quite successfully, because I liked the aspect of independent work with the option to consult with peers or the teacher. 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