atomic structureThe Greek Theorists[edit]

A bust of Democritus (or Democrites), who came up with the idea of indivisible atoms.The earliest known proponent of anything resembling modern atomic theory was the ancient Greek thinker Democritus. He proposed the existence of indivisible atoms as a response to the arguments of Parmenides, and the paradoxes of Zeno.Parmenides argued against the possibility of movement, change, and plurality on the premise that something cannot come from nothing. Zeno attempted to prove Parmenides' point by a series of paradoxes based on difficulties with infinite divisibility.In response to these ideas, Democritus posited the existence of indestructible atoms that exist in a void. Their indestructibility provided a retort to Zeno, and the void allowed him to account for plurality, change, and movement. It remained for him to account for the properties of atoms, and how they related to our experiences of objects in the world.Democritus proposed that atoms possessed few actual properties, with size, shape, and mass being the most important. All other properties, he argued, could be explained in terms of the three primary properties. A smooth substance, for instance, might be composed of primarily smooth atoms, while a sour substance is composed of rough or sharp ones. Solid substances might be composed of atoms with numerous hooks, by which they connect to each other, while the atoms of liquid substances possess far fewer points of connection.Democritus proposed 8 points to his theory of atoms.[1]These are:1. All matter is composed of atoms, which are bits of matter too small to be seen. These atoms CANNOT be further split into smaller portions.2. There is a void, which is empty space between atoms.3. Atoms are completely solid4. Atoms are homogeneous, with no internal structure.5. Atoms are different in: their sizes, their shapes, and their weights.6. Atoms are the building blocks of lifeAlchemy[edit]

Although alchemy was futile, the alchemists did come up with several useful methods, including distillation (shown here).

A fire, shown by Lavoisier to be a chemical reaction and not an element.Empedocles proposed that there were four elements, air, earth, water, and fire and that everything else was a mixture of these. This belief was very popular in the medieval ages and introduced the science of alchemy. Alchemy was based on the belief that since everything was made of only four elements, you could transmute a mixture into another mixture of the same type. For example, it was believed that lead could be made into gold.Alchemy's problem was exposed by Antoine Lavoisier when he heated metallic tin in a sealed flask. A grayish ash appeared on the surface of the melting tin, which Lavoisier heated until no more ash formed. After the flask cooled, he inverted it and opened it underwater. He discovered the water rose one-fifth of the way into the glass, leading Lavoisier to conclude that air itself is a mixture, with one-fifth of it having combined with the tin, yet the other four-fifths did not, showing that air was not an element.Lavoisier repeated the experiment again, substituting mercury for tin, and found that the same happened. Yet after heating gently, he found that the ash released the air, showing that the experiment could be reversed. He concluded that the ash was a compound of the metal and oxygen, which he proved by weighing the metal and the ash, and showing that their combined weight was greater than that of the original metal.Lavoisier then stated that combustion was not an element, but instead was a chemical reaction of a fuel and oxygen.John Dalton[edit]

Different elements, different atoms.

Modern atomic theory was born with Dalton when he published his theories in 1803. His theory consists of five important points, which are considered to be mostly true today:(from Wikipedia) Elements are composed of tiny particles called atoms. All atoms of a given element are identical. The atoms of a given element are different from those of any other element; the atoms of different elements can be distinguished from one another by their respective relative weights. Atoms of one element can combine with atoms of other elements to form chemical compounds; a given compound always has the same relative numbers of types of atoms. Atoms cannot be created, divided into smaller particles, nor destroyed in the chemical process; a chemical reaction simply changes the way atoms are grouped together.We now know that elements have different isotopes, which have slightly different weights. Also, nuclear reactions can divide atoms into smaller parts (but nuclear reactions aren't really consideredchemicalreactions). Otherwise, his theory still stands today.Dmitri Mendeleev[edit]In the late 1800's, Russian scientist Dmitri Mendeleev was credited with creating one of the first organized periodic tables. Organizing each element by atomic weight, he cataloged each of the 56 elements discovered at the time. Aside from atomic weight, he also organized his table to group the elements according to known properties.While writing a series of textbooks, Mendeleev realized he was running out of space to treat each element individually. He began to regularly "linewrap" the elements onto the next line, and create what is now called the periodic table of the elements. Using his table, he predicted the existence of later-discovered elements, such as "eka-aluminum" and "eka-silicon" (gallium and selenium) according to patterns found earlier. His predictions were a success, proving his table to be exceptionally accurate. Later theories, those of the electrons around the atom, explain why elements in the same period, or group, have similar chemical properties. Chemists would later organise each element by atomic number, not atomic weight, giving rise to the modernPeriodic Table of Elements.J.J. Thompson[edit]Discovery of the Electron[edit]

Cathode rays are actually made of electrons.In the year 1889 the British physicist J.J. Thomson discovered the electron. Thomson conducted a number of experiments usingcathode ray tube. Cathode rays are constructed by sealing two electrodes in a glass tube and removing the air from it. When the electrodes are attached to high voltage, a beam of radiation is emitted from the negative electrode. These beams are called cathode rays.Thompson discovered that cathode rays travel in straight lines except when they are bent by electric or magnetic fields. Because the cathode rays bent away from a negatively charged plate, Thomson concluded that these rays are made of negatively charged particles; today we call them electrons. Thompson found that he could produce cathode rays using electrodes of various materials. He then concluded that electrons were found in all atoms and are over a thousand times smaller than protons.The "Plum Pudding" Atomic Model[edit]Soon after the discovery of the electron, Thompson began speculating on the nature of the atom. He suggested a "plum pudding" model. In this model the bits of "plum" were the electrons which were floating around in a "pudding" of positive charge to match that of the electrons and make an electrically neutral atom. A modern illustration of this idea would be a chocolate chip cookie, with the chips representing negatively charged electrons and the dough representing positive charge.Rutherford[edit]

The results of the gold foil experiment disproved the "plum pudding" model: the alpha particles should have passed through (top), but a few of them deflected at large angles (bottom).Ernest Rutherford is known for his famousgold foil experimentin 1911. Alpha particles, which are heavy and positively charged (actually, helium nuclei, but that's beside the point), were fired at a very thin layer of gold. Most of the alpha particles passed straight through, as expected. According to the plum pudding modelallof the particles should have slowed as they passed through the "pudding", but none should have been deflected. Surprisingly, a few alpha particles were deflected back the way they came. He stated that it was "as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you."The result of the experiment allowed Rutherford to conclude that the plum pudding model is wrong. Atoms have anucleus, very small and dense, containing the positive charge and most of the atom's mass. The atom consists of mostly empty space. The electrons are attracted to the nucleus, but remain far outside it.Niels Bohr[edit]

The Bohr model of the atom has shells with numbered spherical energy levels - the larger numbers mean larger spheres and higher energy levels. The wave exiting the picture on the left has come from an electron jump, resulting in a photon. (Level sizes not to scale.)Bohr created his own model of the atom, improving on Rutherford's. Bohr created an equation that could predict thespectral linesof the hydrogen atom. He then realized that electrons must orbit the nucleus in "shells", each with a certain energy level. An atom will absorb and release photons that have a specific amount of energy. The energy is the result of an electron jumping to a different shell. The Bohr model depicts the atom as a nucleus with electrons orbiting around it at specific distances.Millikan[edit]Robert Millikanis accredited for the "Oil Drop Experiment", in which the value of the electron charge was determined. He created a mechanism where he could spray oil drops that would settle into a beam of X rays. The beam of X rays caused the oil drops to become charged with electrons. The oil droplets were in between a positively charged plate and a negatively charged plate which, when proper electric voltage was applied, caused the oil droplet to remain still. Robert Millikan measured the diameter of each individual oil drop using a microscope.Millikan was able to calculate the mass of each oil droplet because he knew the density of the oil (). Using the mass of each oil droplet and the equation for the force of gravitational attraction (which he rearranged fromto, whereis the mass of each individual oil droplet,is the acceleration due to gravity, andis the electrical force which equals force in the first equation), Millikan was able to find the value of the charge of the electron,.The X rays, however, did not always produce an oil drop with only one negative charge. Thus, the values Millikan obtained may have looked like this: coulomb coulomb coulomb coulombMillikan found that these values all had a common divisor:coulomb. He concluded that different values occurred because the droplets acquired charges of -5, -4, -3, and -2, as in this example. Thus, he stated that the common divisor,coulomb, was the charge of the electron.

Charging by ConductionCharging by Conduction is when two charge object interact to a neutral object. Charging by Conduction are also called Charging by Contact. There are one device thats is called an electroscope. By charging conduction, a charge object should have touch the charge electroscope and transfer it charge to it.

An example is when you walk to the door and you rub your feet, well thats is charging by rubbing. And then when u touch the doorknob those charges on your hand are leaving you and there going into the doorknob. And thats is called charging by contact.

Charging by ConductionIn the previous two sections of Lesson 2, the process ofcharging by frictionandcharging by inductionwere described and explained. In this section of Lesson 2, a third method of charging -charging by conduction-will be discussed. As was the case for charging by friction and charging by induction, the process of conduction will be described and explained using numerous examples of electrostatic demonstrations and lab experiments.Charging by conduction involves the contact of a charged object to a neutral object. Suppose that a positively charged aluminum plate is touched to a neutral metal sphere. The neutral metal sphere becomes charged as the result of being contacted by the charged aluminum plate. Or suppose that a negatively charged metal sphere is touched to the top plate of a neutralneedle electroscope. The neutral electroscope becomes charged as the result of being contacted by the metal sphere. And finally, suppose that an uncharged physics student stands on an insulating platform and touches a negatively charged Van de Graaff generator. The neutral physics student becomes charged as the result of contact with the Van de Graaff generator. Each of these examples involves contact between a charged object and a neutral object. In contrast to induction, where the charged object is brought near but never contacted to the object being charged, conduction charging involves making the physical connection of the charged object to the neutral object. Because charging by conduction involves contact, it is often calledcharging by contact.Charging by Conduction Using a Negatively Charged ObjectTo explain the process of charging by contact, we will first consider the case of using a negatively charged metal sphere to charge a neutral needle electroscope. Understanding the process demands that you understand that like charges repel and have an intense desire to reduce their repulsions by spreading about as far as possible. A negatively charged metal sphere has an excess of electrons; those electrons find each other repulsive and distance themselves from each other as far as possible. The perimeter the sphere is the extreme to which they can go. If there was ever a conducting pathway to a more spacious piece of real estate, one could be sure that the electrons would be on that pathway to thegreener grassbeyond. In human terms, electrons living in the same home despise each other and are always seeking a home of their own or at least a home with more rooms.Given this understanding of electron-electron repulsions, it is not difficult to predict what excess electrons on the metal sphere would be inclined to do if the sphere were touched to the neutral electroscope. Once the contact of the sphere to the electroscope is made, a countless number of excess electrons from the sphere move onto the electroscope and spread about the sphere-electroscope system. In general, the object that offers the most space in which to "hang out" will be the object thathousesthe greatest number of excess electrons. When the process of charging by conduction is complete, the electroscope acquires an excess negative charge due to the movement of electrons onto it from the metal sphere. The metal sphere is still charged negatively, only it has less excess negative charge than it had prior to the conduction charging process.

Charging by Conduction Using a Positively Charged ObjectThe previous example of charging by conduction involved touching a negatively charged object to a neutral object. Upon contact, electrons moved from the negatively charged object onto the neutral object. When finished, both objects were negatively charged. But what happens if a positively charged object is touched to a neutral object? To investigate this question, we consider the case of a positively charged aluminum plate being used to charge a neutral metal sphere by the process of conduction.The diagram below depicts the use of a positively charged aluminum plate being touched to a neutral metal sphere. A positively charged aluminum plate has an excess of protons. When looked at from an electron perspective, a positively charged aluminum plate has a shortage of electrons. In human terms, we could say that each excess proton is rather discontented. It is not satisfied until it has found a negatively charged electron with which to co-habitate. However, since a proton is tightly bound in the nucleus of an atom, it is incapable of leaving an atom in search of that longed-for electron. It can however attract a mobile electron towards itself. And if a conducting pathway is made between a collection of electrons and an excess proton, one can be certain that there is likely an electron that would be willing to take the pathway. So when the positively charged aluminum plate is touched to the neutral metal sphere, countless electrons on the metal sphere migrate towards the aluminum plate. There is a mass migration of electrons until the positive charge on the aluminum plate-metal sphere system becomes redistributed. Having lost electrons to the positively charged aluminum plate, there is a shortage of electrons on the sphere and an overall positive charge. The aluminum plate is still charged positively; only it now has less excess positive charge than it had before the charging process began.

The above explanation might raise a rather difficult question: Why would an electron on the previously neutral metal sphere desire to move off the metal sphere in the first place? The metal sphere is neutral; every electron on it must be satisfied since there is a corresponding proton present. What would possibly induce an electron to go through the effort of migrating to a different territory in order to have what it already has?The best means of answering this question requires an understanding of the concept of electric potential. But since that concept does not arise until the next unit ofThe Physics Classroom, a different approach to an answer will be taken. It ends up that electrons and protons are not as independent and individualized as we might think. From a human perspective, electrons and protons can't be thought of as independent citizens in a free enterprise system of government. Electrons and protons don't actually do what is best for themselves, but must be more social-minded. They must act like citizens of a state where the rule of law is to behave in a manner such that the overall repulsive affects within the society at large are reduced and the overall attractive affects are maximized. Electrons and protons will be motivated not by what is good for them, but rather bywhat is good for the country. And in this sense, a country's boundary extends to the perimeter of the conductor material that an excess electron is within. And in this case, an electron in the metal sphere is part of a country that extends beyond the sphere itself and includes the entire aluminum plate. So by moving from the metal sphere to the aluminum plate, an electron is able to reduce the total amount of repulsive affects within that country. It serves to spread the excess positive charge over a greater surface area, thus reducing the total amount of repulsive forces between excess protons.Law of Conservation of ChargeIn each of the other methods of charging discussed in Lesson 2 -charging by frictionandcharging by induction- the law of conservation of charge was illustrated. The law of conservation of charge states that charge is always conserved. When all objects involved are considered prior to and after a given process, we notice that the total amount of charge among the objects is the same before the process starts as it is after the process ends. The same conservation law is observed during the charging by conduction process. If a negatively charged metal sphere is used to charge a neutral electroscope, the overall charge before the process begins is the same as the overall charge when the process ends. So if before the charging process begins, the metal sphere has 1000 units of negative charge and the electroscope is neutral, the overall charge of the two objects in thesystemis -1000 units. Perhaps during the charging process, 600 units of negative charge moved from the metal sphere to the electroscope. When the process is complete, the electroscope would have 600 units of negative charge and the metal sphere would have 400 units of negative charge (the original 1000 units minus the 600 units it transferred to the electroscope). The overall charge of the two objects in the system is still -1000 units. The overall charge before the process began is the same as the overall charge when the process is completed. Charge is neither created nor destroyed; it is simply transferred from one object to another object in the form of electrons.Conduction Charging Requires a ConductorIn all the above examples, the charging by conduction process involved the touching of two conductors. Does contact charging have to occur through the contact of two conductors? Can an insulator conduct a charge to another object upon touching? And can an insulator be charged by conduction? A complete discussion of these questions can get messy and quite often leads to asplitting of hairsover the definition of conduction and the distinction between conductors andinsulators. The belief is taken here that only a conductor can conduct charge to another conductor. The process of noticeably charging an object by contact involves the two contacting objects momentarily sharing the net excess charge. The excess charge is simply given a larger area over which to spread in order to reduce the total amount of repulsive forces between them. This process demands that the objects be conductors in order for electrons to move about and redistribute themselves. An insulator hinders such a movement of electrons between touching objects and about the surfaces of the objects. This is observed if an aluminum pie plate is placed upon a charged foam plate. When the neutral aluminum plate is placed upon the charged foam plate, the foam plate does not conduct its charge to the aluminum. Despite the fact that the two surfaces were in contact, charging by contact or conduction did not occur. (Or at least whatever charge transfer might have occurred was not noticeable by the customary means of using an electroscope, using a charge testing bulb or testing for its repulsion with a like-charged object.)Many might quickly suggest that they have used a charged insulator to charge a neutral electroscope (or some other object) by contact. In fact, a negatively charged plastic golf tube can used to charge an electroscope. The plastic tube is touched to the top plate of the electroscope. On most occasions, the plastic tube is even rubbed or rolled across the plate of the electroscope? Wouldn't this be regarded as charging by conduction? No. Not really. In this case, it is more thanlikely that the charging occurred by some process other than conduction. There was not a sharing of charge between the plastic tube and the metal parts of the electroscope. Of course, once some excess charge is acquired by the electroscope, that excess charge distributes itself about the surface of the electroscope. Yet the charge is not uniformly shared between the two objects. The protons and electrons within both the plastic golf tube and the electroscope are not acting together to share excess charge and reduce the total amount of repulsive forces.The charging of an electroscope by contact with a negatively charged golf tube (or any charged insulating object) would best be described ascharging by lightning. Rather than being a process in which the two objects act together to share the excess charge, the process could best be described as the successful effort of electrons to burst through the space (air) between objects. The presence of a negatively charged plastic tube is capable of ionizing the air surrounding the tube and allowing excess electrons on the plastic tube to be conducted through the air to the electroscope. This transfer of charge can happen with or without touching. In fact, on a dry winter day the process of charging the metal electroscope with the charged insulator often occurs while the insulator is some distance away. The dry air is more easily ionized and a greater quantity of electrons is capable of bursting through the space between the two objects. On such occasions, a crackling sound is often heard and a flash of light is seen if the room is darkened. This phenomenon, occurring from several centimeters away, certainly does not fit the description of contact charging.A charged insulating object is certainly capable of transferring its charge to another object. The result of the charge transfer will be the same as the result of charging by conduction. Both objects will have the same type of charge and the flow of electrons is in the same direction. However, the process and the underlying explanations are considerably different. In the case of charging an object with a charged insulator, the contact is not essential. Contacting the object simply reduces the spatial separation betweentouching atomsand allows charge to arc and spark its way between objects. Rubbing or rolling the insulating object across the conductor's surface facilitates the charging process by bringing a greater number of atoms on the insulator in close proximity to the conductor that is receiving the charge. The two materials do not make any effort to share charge nor to act as a single object (with auniform electric potential) in an effort to reduce repulsive affects.Is this distinction between charging by conduction and charging by lightning a splitting of hairs? Perhaps. For certain, each process involves a transfer of charge from one object to another object, yielding the same result - two like-charged object. Yet, distinguishing between the two forms of charging is more consistent with the customary view that insulators are not conductors of charge. It also serves to explain why some insulators clearly do not always transfer their charge upon contact. This phenomenon of charging by lightning will be revisited inLesson 4during a discussion of electric fields and lightning discharges.Check Your UnderstandingUse your understanding of charge to answer the following questions. When finished, click the button to view the answers.1. A neutral metal sphere is touched by a negatively charged metal rod. As a result, the sphere will be ____ and the metal rod will be ____. Select the two answers in their respective order.a. positively chargedb. negatively chargedc. neutrald. much more massivee. ... not enough information to tell2. A neutral metal sphere is touched by a negatively charged metal rod. During the process, electrons are transferred from the _____ to the _____ and the sphere acquires a _____ charge.a. neutral sphere, charged rod, negativeb. neutral sphere, charged rod, positivec. charged rod, neutral sphere, negatived. charged rod, neutral sphere, positivee. ... nonsense! None of these describe what occurs.3. A neutral metal sphere is touched by a positively charged metal rod. During the process, protons are transferred from the _____ to the _____ and the sphere acquires a _____ charge.a. charged rod, neutral sphere, negativeb. charged rod, neutral sphere, positivec. neutral sphere, charged rod, negatived. neutral sphere, charged rod, positivee. ... nonsense! None of these describe what occurs.4. A metal sphere is electrically neutral. It is touched by a positively charged metal rod. As a result, the metal sphere becomes charged positively. Which of the following occur during the process? List all that apply.a. The metal sphere gains some protons.b. Electrons are transferred from the sphere to the rod.c. The metal sphere loses electrons.d. The overall charge of the system is conserved.e. Protons are transferred from the rod to the sphere.f. Positive electrons are moved between the two objects.

An electroscopeAn electroscope is a device that can be used to test for the presence of charge, or that can be charged. An electroscope is made from conducting material (generally metal). Charge is free to flow on a conductor, and if you put charge at a particular point it will distribute itself over the surface of the conductor.An electroscope generally has a rotating arm indicating the presence of a net charge. On the electroscope we'll use, when the electroscope is uncharged the arm is usually vertical, and when the electroscope is charged the arm moves away from vertical. This is true as long as there are no charged objects nearby - in a few minutes we'll discuss what happens when there are charged objects nearby.

conductors and insulators

IntroductionBy now you should be well aware of the correlation between electrical conductivity and certain types of materials. Those materials allowing for easy passage of free electrons are calledconductors, while those materials impeding the passage of free electrons are calledinsulators.Unfortunately, the scientific theories explaining why certain materials conduct and others don't are quite complex, rooted in quantum mechanical explanations in how electrons are arranged around the nuclei of atoms. Contrary to the well-known "planetary" model of electrons whirling around an atom's nucleus as well-defined chunks of matter in circular or elliptical orbits, electrons in "orbit" don't really act like pieces of matter at all. Rather, they exhibit the characteristics of both particle and wave, their behavior constrained by placement within distinct zones around the nucleus referred to as "shells" and "subshells." Electrons can occupy these zones only in a limited range of energies depending on the particular zone and how occupied that zone is with other electrons. If electrons really did act like tiny planets held in orbit around the nucleus by electrostatic attraction, their actions described by the same laws describing the motions of real planets, there could be no real distinction between conductors and insulators, and chemical bonds between atoms would not exist in the way they do now. It is the discrete, "quantitized" nature of electron energy and placement described by quantum physics that gives these phenomena their regularity.When an electron is free to assume higher energy states around an atom's nucleus (due to its placement in a particular "shell"), it may be free to break away from the atom and comprise part of an electric current through the substance. If the quantum limitations imposed on an electron deny it this freedom, however, the electron is considered to be "bound" and cannot break away (at least not easily) to constitute a current. The former scenario is typical of conducting materials, while the latter is typical of insulating materials.Some textbooks will tell you that an element's conductivity or nonconductivity is exclusively determined by the number of electrons residing in the atoms' outer "shell" (called thevalenceshell), but this is an oversimplification, as any examination of conductivity versus valence electrons in a table of elements will confirm. The true complexity of the situation is further revealed when the conductivity of molecules (collections of atoms bound to one another by electron activity) is considered.A good example of this is the element carbon, which comprises materials of vastly differing conductivity: graphite and diamond. Graphite is a fair conductor of electricity, while diamond is practically an insulator (stranger yet, it is technically classified as asemiconductor, which in its pure form acts as an insulator, but can conduct under high temperatures and/or the influence of impurities). Both graphite and diamond are composed of the exact same types of atoms: carbon, with 6 protons, 6 neutrons and 6 electrons each. The fundamental difference between graphite and diamond being that graphite molecules are flat groupings of carbon atoms while diamond molecules are tetrahedral (pyramid-shaped) groupings of carbon atoms.If atoms of carbon are joined to other types of atoms to form compounds, electrical conductivity becomes altered once again. Silicon carbide, a compound of the elements silicon and carbon, exhibits nonlinear behavior: its electrical resistance decreases with increases in applied voltage! Hydrocarbon compounds (such as the molecules found in oils) tend to be very good insulators. As you can see, a simple count of valence electrons in an atom is a poor indicator of a substance's electrical conductivity.All metallic elements are good conductors of electricity, due to the way the atoms bond with each other. The electrons of the atoms comprising a mass of metal are so uninhibited in their allowable energy states that they float freely between the different nuclei in the substance, readily motivated by any electric field. The electrons are so mobile, in fact, that they are sometimes described by scientists as anelectron gas, or even anelectron seain which the atomic nuclei rest. This electron mobility accounts for some of the other common properties of metals: good heat conductivity, malleability and ductility (easily formed into different shapes), and a lustrous finish when pure.Thankfully, the physics behind all this is mostly irrelevant to our purposes here. Suffice it to say that some materials are good conductors, some are poor conductors, and some are in between. For now it is good enough to simply understand that these distinctions are determined by the configuration of the electrons around the constituent atoms of the material.An important step in getting electricity to do our bidding is to be able to construct paths for electrons to flow with controlled amounts of resistance. It is also vitally important that we be able to prevent electrons from flowing where we don't want them to, by using insulating materials. However, not all conductors are the same, and neither are all insulators. We need to understand some of the characteristics of common conductors and insulators, and be able to apply these characteristics to specific applications.Almost all conductors possess a certain, measurable resistance (special types of materials calledsuperconductorspossess absolutely no electrical resistance, but these are not ordinary materials, and they must be held in special conditions in order to be super conductive). Typically, we assume the resistance of the conductors in a circuit to be zero, and we expect that current passes through them without producing any appreciable voltage drop. In reality, however, there will almost always be a voltage drop along the (normal) conductive pathways of an electric circuit, whether we want a voltage drop to be there or not:

In order to calculate what these voltage drops will be in any particular circuit, we must be able to ascertain the resistance of ordinary wire, knowing the wire size and diameter. Some of the following sections of this chapter will address the details of doing this. REVIEW: Electrical conductivity of a material is determined by the configuration of electrons in that materials atoms and molecules (groups of bonded atoms). All normal conductors possess resistance to some degree. Electrons flowing through a conductor with (any) resistance will produce some amount of voltage drop across the length of that conductor.

conservation of charge

conservation of chargen.A principle stating that the total electric charge of an isolated system remains constant regardless of changes within the system.

The American Heritage Dictionary of the English Language, Fourth Edition copyright 2000 by Houghton Mifflin Company. Updated in 2009. Published byHoughton Mifflin Company. All rights reserved.

conservation of chargen(Physics / General Physics) the principle that the total charge of any isolated system is constant and independent of changes that take place within the systemCollins English Dictionary Complete and Unabridged HarperCollins Publishers 1991, 1994, 1998, 2000, 2003

conservation of chargeA conservation law stating that the total electric charge of a closed system remains constant over time, regardless of other possible changes within the system.

The Law of Conservation of Change states that electrical charges cannot be made or destroyed. Whatever changes a system may go through, the net charge which is the number of positive charge less the number of negative charges will not change. That means it will always be constant. The only possible way this net charge can be changed is if some charge is removed from the system or added to it.1 Additional Answerlaw of conservation of charge- Definition(n.) The principle that the total electric charge of a system is constantSource:Dictionary.comQ&A Related to "Law of Conservation of Charge?"What isLawofConservationofCharge?Just like other conservation laws, it means that there is something - in this case, the amount of electrical charge - that won't change over time.http://wiki.answers.com/Q/What_is_Law_of_Conservat...

What is thelawofconservationofchargestates?changes are not created or destroyed (novanet).http://wiki.answers.com/Q/What_is_the_law_of_conse...

What is thelawofconservationof electriccharge?According to conservation of electric charge ,the total charge on an isolated system remains constant. ( By isolated system we mean the system in which there is no external disturbancehttp://wiki.answers.com/Q/Which+of+the+following+a...

What is theLawofConservationof Mass?The law of conservation of mass states that a mass will remain consistent over time. This means that even if you light something on fire the elements that it is broken down to will

charge quantization

What is quantization of electric charge?It is the property by which any charge lives only in separate collection or bundle of specific minimum charge. Positive and negative charge in the equation is denoted by q. The equation is shown below:q=nen can have both negative as well as positive values. E.g. 1, 2, 3. and -1,-2,-3,-4..e in the above equation means charge having a value of 1.6 X 10-19.The charge present on both the protons and electrons is denoted by e but the difference is that the charge on an electron is (-e) and on proton is (+e).Further study will show that the quantization is a universal law of nature.Email This Page To Your FriendPrint This PageCategory:Electrostatics4 Responses to " What is quantization of electric charge? "1. nitishsays:June 3, 2010 at 12:37 amwhat is dipole moment?2. Razorsays:May 3, 2011 at 7:06 pmDipole moment is defined asP=ql whereas p is a dipole,q is the charge and l is the distance between the two charges of equal and opposite magnitude.3. Abhisheksays:August 28, 2011 at 3:24 amHow is it possible to create or destroy net charge?4. Suhaibsays:December 13, 2011 at 7:41 amWhy charge can not be in fraction of +e or -e?