Sunday, January 26, 2020
The quantum nature of charge
The quantum nature of charge INTRODUCTION In this experiment you will experimentally determine the quantum nature of charge. Robert Millikan was awarded the Nobel Prize in physics in 1923 for the oil drop experiment. A simplistic schematic of his apparatus is shown below A spherical drop of oil, falling through a viscous medium like air, will quickly reach a constant velocity. When it reaches this equilibrium position, the viscous force is balanced by other forces acting on the drop, such as gravity, buoyant forces from the air, electrical forces, etc. In this experiment an electrical force of varying magnitude is introduced to change the motion of the falling drop by an ionization source. By measuring the velocity of the oil drop under different conditions the amount of charge on the drop may be determined. If the charge on the drop is an integer multiple of the fundamental unit of charge (the electron), then one will be able to confirm the quantization of charge.[1] WHAT IS MIILIKAN OIL DROP EXPERIMENT Oil-drop experiment was the first direct and compelling measurement of the electric charge of a single electron. It was performed originally in 1909 by the American physicist Robert A. Millikan. Using a perfume atomizer, he sprayed tiny drops of oil into a transparent chamber. At the top and bottom were metal plates hooked to a battery, making one positive (red in animation) and the other negative (blue in animation). Since each droplet picked up a slight charge of static electricity as it traveled through the air, the speed of its motion could be controlled by altering the voltage on the plates. When the space between the metal plates is ionized by radiation (e.g., X rays), electrons from the air attach themselves to oil droplets, causing them to acquire a negative charge. Millikan observed one drop after another, varying the voltage and noting the effect. After many repetitions he concluded that charge could only assume certain fixed values. The smallest of these portions was none other than the charge of a single electron.[3] OUTLINE OF EXPERIMENT Very small oil drops are produced by spraying air over oil (or premade latex spheres are used) into a drift chamber. The oil drops fall but reach terminal velocity very quickly because of their large area to mass ratio. The terminal velocity is measured using a microscope with a graduated scale and a stopwatch. If the drop is charged it can then be moved upward (or forced down) using the electric field produced by metal plates above and below the experimental chamber. The upward and downward terminal velocities are also measured. APPARATUS Robert Millikans apparatus incorporated a parallel pair of horizontal metal plates. By applying a potential difference across the plates, a uniform electric field was created in the space between them. A ring of insulating material was used to hold the plates apart. Four holes were cut into the ring, three for illumination by a bright light, and another to allow viewing through a microscope. A fine mist of oil droplets was sprayed into a chamber above the plates. The oil was of a type usually used invacuum apparatus and was chosen because it had an extremely lowvapour pressure. Ordinary oil would evaporate away under the heat of the light source causing the mass of the oil drop to change over the course of the experiment. Some oil drops became electrically charged through friction with the nozzle as they were sprayed. Alternatively, charging could be brought about by including an ionising radiation source (such as anX-ray tube). The droplets entered the space between the plates and, because they were charged, could be made to rise and fall by changing the voltage across the plates.[2] Principal The method is based upon the observation of the rate of motion of a small oil drop. Under free fall due to gravity and under the application of suitable electric field. By adjusting the electric field suitably, a given oil drop can be made to move up or down or even kept balanced in the field of view for sufficiently long time and a series of observation can be made. Construction Robert Millikan apparatus in corporate a parallel pair of horizontal metal plates. By applying a potential difference across the pates a uniform electric was created in space between them a ring of insulating material was used to hold the plate apart four holes were cut into the ring, three for illumination by a bright light and another to allow viewing through a microscope. Method Initially the oil drops are allowed to fall between the plates with the electric field turned off. Millikans basic idea was to measure the rate of fall of a single drop acted on by gravity and drag forces, apply stokes law to determine the drop radius and mass, then to measure its upward velocity in an opposing electric field and hence determine the total charge on an individual drop. The field is then turned on and if it is large enough some of the drops will starts to rise. Oil droplets charged by an atomizer are allowed two pass to small hole in the upper plate of parallel plate capacitor. If these droplets are illuminated from the side. They appear as brilliant stars against a dark background and the rate of fall of individual drops may be determined. If an electrostatic field of several thousand volts per meter is applied to the capacitor plates the drop may moves slowly upwards typically at rates of hundreds of a centimeter per second. Because the rate of fall is comparable a single droplets with constant mass and radius may be followed for hours alternately rising and falling by simply turning the electric field on and off. The atomicity of charge is shown directly by observation that after a long series of measurements of constant upward velocities one observe discontinuous charge or jump to a different upward velocity. This discontinuous charge is caused by the attraction of an ion to the charged droplet and consequent charge in droplet charge. Such charge become more frequent when a source of ionizing radiation is placed between the plates. The quantitative analysis of the Millikan experiments starts with Newtons second law applied to the oil drop . ?y-= may because the drag force is large a constant velocity of fall is quickly achieved and all measurement are made for the case ay = 0 or ?fy=0. If we assume that magnitude of the drag force is proportional to the speeds Cv. Cv-mg=0(field off) q1E -mg- Cv1=0 (field on) Eliminate c from this expression gives q1 = mg/E (v+v1/v) when the droplet undergoes a discontinuous change in its upward speed from v1 to v2 its new charge q2 is given by q2 = mg/E (v+v2/v) Dividing q1 by q2 q1/q2 = v+ v1/v+v2 Electric Charge Electric charge is an intrinsic characteristics of the fundamental particles making up those objects that is it is a property that comes automatically with those particles wherever they exist. The vast amount of charge in an everyday object is usually hidden because the object contains equal amounts of the two kinds of charge positive and negative charge. With such an equality or balance of charge. The object is said to be electrically neutral that is it contains no net charge. If the two type of charge are not in balance then there is a net charge. Charge object interact by exerting forces on one another charges with the same electrical sign repel each other and charges with opposite electrical attract each other. Stokes law When a solid body moves through a fluid, the fluid is contact with the solid is dragged with it relative velocities are stabilized between the layers of the fluid near the solid so that viscous force start operating. The fluid exerts viscous force on the solid oppose the motion the of the solid. The magnitude of the viscous force depends on the shape and size of the solid body. Its speed and the coefficient of the viscosity of the fluid. Suppose a spherical body of radius r moves at a speed v through fluid of viscosity ?. The viscous force f acting on the body depends on r, v and ?. Assuming that the force is proportional to the viscous powers of these quantities, we can obtain the dependence through dimensional analysis. F= kra vb ?c Where k is the dimensional constant. Dimensional constant k = 6 p, so that the equation becomes F = 6 p ? r v Viscosity When a layer of a fluid slips or tends to slip on another layer in contact. The two layer exert tangential force on each other. The direction such that relative motion between the layer is opposed. This property of a fluid to oppose relative motion between its layer is called viscosity. The force between the layers opposing relative motion between them are known as the forces of viscosity. Thus, viscosity may be through of as the internal friction of a fluid in motion. If a solids surface is kept in contact with a fluid and is moved, force of viscosity appear between the solid surface and the fluid layer in contact. The flid in contact is dragged with solid and there is no relative slipping. When a boat moves slowly on the water calm river. The water in contact wwitth the boat is dragged with it, whereas the water in contact with the bed of the river remains at the rest. Velocities of the different layer are coefficient. Let v be th velocity of the layer at a distance from the bed and v+dv be the velocity at a distance z+dz. Thus the velocity differs by dv in going through a distance dz perpendicular to it. The quantity dv/dz is called the velocity gradient. The force of viscosity between two layers of a fluid is proportional to the velocity gradient in the direction perpendicular to the layers. Also the force is proportion to the area of the layer. Thus if F is the force exerted by a layer of area a on a layer in contact. F a A and F a dv/dz F = ? A dv/dz The negative slide is included as the forceis fractional in the nature and opposes relative motion. The constant of proportionality ? is called the coefficient of viscosity. The S.I unit of viscosity is N-s/m2 and CGS unit is dyne sec/cm2+ is in common use and is called a poise. IMPORTANCE OF MILLIKAN METHOD It is a direct and a prices method for determination of electronic charge, yielding fairly accurate results. It proves that an electron carries a definite amount of charge and that the charge on an ion , positive or negative, is numerically equal to that on electron. It establishes that electricity is atomic in nature. Avogadros number- The knowledge of the charge on an electron helps to determine Avogadros number which is the number of molecules contained in 1 gram molecule of an element. Gram atom and gram molecule of an element is its weight in gram numerically equal to its atomic weight or molecular weight respectively. CONCLUSION REFERENCE http://facultyfiles.deanza.edu/gems/lunaeduardo/MillikanOilDropExperiment.pdf http://en.wikipedia.org/wiki/Oil-drop_experiment#Apparatus http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=357.0
Friday, January 17, 2020
How The Adoration Of Jenna Fox Essay
The Adoration Of Jenna Fox relates to real life because of meeting new people, feelings and also as the Kirkus Reviews said ââ¬â ââ¬Å"Outstanding examination of identity, science and ethics. Reason reveal the truth layer by layer, maintain taut suspense and psychological realism as she probes philosophical notions of personhood.â⬠Protective parents, Jenna had very protective ones but for a reason, In the book Jenna almost dies and get cloned with ââ¬Å"bio gelâ⬠to make a new body that she can live in with the same memories and feelings. Claire is very protective of Jenna because she doesnââ¬â¢t want anyone figuring out of knowing that she is not a human but a clone. Claire does not want anyone to know Jenna of make contact with her, but Jenna is a very curious young woman and is eager to start a new life with new people ââ¬Å"I should be afraid. Mother would want me to be afraid. But other than Mother, Father and Lily, Mr bender is the only human being I have seen since I woke up. I want to speak to someone who doesnââ¬â¢t know me.â⬠(pg. 17) Being curious. Jenna Fox is a very curious and questioning person, she is always thinking new things and as has so much to learn and even though some of it is really bad she is still very eager to find out about her past and figure out her future. When she tells a very close person to her what she is and she is scared and frightened to see what their reaction is. ââ¬Å" He stares at me. His face is stiff. Frightening. I feel weak. What have I done? I shouldââ¬â¢ve kept quiet. Listened to mother. To Lily. I want to take back every word, but it is too late.â⬠(Pg.156) Finding herself, Jennaââ¬â¢s brain is really her own, with the rest uploaded onto her brain. When Jenna finds out about the accident, she realises why remaking her identity so difficult. She doesnââ¬â¢t know who she is, and she is trying to uncover her past. We see that Jennaââ¬â¢s parents maybe did not make the best decision, as Jenna struggles to remake her identity, going through lots of ups and downs throughout the book. Using the available technology,à Matthew and Claire re-created their perfect daughter. But, as Jenna finds remaking her identity difficult, this maybe says that her parents might have been too early and not thought out in their decision to save her. They made the right choice, but Jenna is not without her problems. In conclusion, The Adoration Of Jenna Fox relates to the real world in many ways apart from being made more than half out of ââ¬Å"bio gelâ⬠But she experiences many simular things to modern day teenagers. Such as having parents that really care about her, learning new things at different paces and finding herself throughout life.
Thursday, January 9, 2020
Persuasive Essay On Factory Farming - 703 Words
Persuasive Essay #2 Factory farming describes how large modern farms produce food in large quantities for a small cost. Factory farms, however, pollute the air by releasing harmful gases. They practice deforestation to claim more farmland. Factory farms pollute our waters to keep costs low. Factory farming is harming the environment Nobody denies that the need for more food grows with the global population. Factory farms seem to be a solution to this problem since they produce mass quantities of food for cheap compared to their organic counterparts, which are forty-seven percent more expensive (Consumer Reports). The factory farming business, however, is not the best way to feed more people since it pollutes the environment. The factoryâ⬠¦show more contentâ⬠¦More carbon dioxide in the atmosphere will warm the planet, and more of it in the ocean will acidify the ocean, making it uninhabitable to a growing number of marine species. Factory farms are destroying forests in order to grow more food a nd make more money. Furthermore, factory farms pollute drinking water sources. Manure and fertilizers are rich in nitrates and phosphates, which are very unhealthy for living things. They pollute groundwater sources by seeping in through lagoons of waste sewage that factory farms create. Lagoons of animal feces and spent fertilizers are a very cheap way of dealing with waste (NRDC). The chemicals travel through the soil to groundwater that the local communities depend on. Ingesting nitrate tainted water will lower the amount of oxygen a person can intake. This can lead to death for infants. Some of the pollutants can reach open waters if they are carried by rain or irrigation water, called runoff. Runoff pollutes ponds, lakes, oceans, and other open bodies of water. Polluted waters with high levels of nitrates kill fish, aquatic plants, and other aquatic organisms because they experience the same problems with oxygen intake. High levels of phosphorus in our waters cause algae blooms in open bodies of water. Algae blooms disrupt the ecosystem in the water and kill the organisms living in the water. They use up all the oxygen inShow MoreRelatedPersuasive Essay On Factory Farming1343 Words à |à 6 Pagesconsume probably comes from factory farms. Factory farms consist of large buildings that confine animals in order to prevent diseases but also to produce food fast and more efficiently. Factory farms help produce more food to feed the world. World hunger is a growing issue and has been an issue for quite some time. Factory farms increase production and help feed the world. Due to an increase in population factory farms holds the worldââ¬â¢s food supply in check. 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Wednesday, January 1, 2020
The 3 Houses Of Theu.s Government - 866 Words
The 3 houses of the U.S Government The houses consist of the Judicial, Legislative, and Executive branches. The foundation of these separated powers are based on the U.S Constitution. Originally modified from the Articles of Confederation. The limited but functional Articles of Confederation was revised because our founding fathers from 1788 had collective action problems. Like gun control, military, taxes, personal rights etc. Because of these issues James Madison, Alexander Hamilton and John Jay and several others constructed the U.S Constitution. What came with the constitution is the first house, known as the Supreme Court. The second house is where Congress gather committees and sub committees to aid law making. And the last house is the President. The houses all have different duties and each decision must be approved by one or both parties. Also known as checks and balances. This is crucial because there is no one branch holding too much power. In this paper I am going to discuss three examples of checks and ba lances between the three houses. The Powerful Supreme Court These judges are experts in law and are the decision makers of whether or not a decision made by the president and congress is unconstitutional. There are 5 associate judges with 1 Chief Justice. These judges are appointed by the president and then confirmed by congress. Also included with keeping the president and congress in check. They get to serve as judges for the rest of their lives if theyShow MoreRelatedCopyright Of The Intellectual Property1871 Words à |à 8 Pageswere arrested for violating copyrights. Local police with the help of state and federal partners and ICE launched operational digital pirates which is an investigation into the identification of intellectual property rights violation in Puerto Rico. 3.)Adidas a multinational corporation was using three stripe marks as a logo since 1952, but it registered its logo as trademark recently. Payless other similar kind of company was also confusingly using similar kind of logo. Adidas registered its logoRead MoreQuestions On Intellectual Property Rights1898 Words à |à 8 Pagesarrested for violating copyrights. Local police with the help of state and federal partners and ICE launched operational digital pirates which is an investigation into the identification of intellectual property rights violation in Puerto Rico. 3.)Adidas a multinational corporation was using three stripe marks as a logo since 1952, but it registered its logo as trademark recently. Payless other similar kind of company was also confusingly using similar kind of logo. Adidas registered itsRead MoreFactors Affecting Class Attendance of Selected Bachelor of Science in Cruise Line Operatons Students6991 Words à |à 28 Pages.............................. 9 foreign Literature ............................. 12 Local Studies .................................. 25 Foreign Studies ................................ 25 Synthesis of Related Literature and Studies .... 29 3. Methodology Research Design ................................ 34 Population and Sampling Procedure .............. 35 Respondents of theStudy ....................... 36 Research Instruments ........................... 40 Data Gathering Procedure
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