You may wonder why we have to start with such a basictopic. The factor is the there room a number of differences in theconventions the engineers and scientists and also others use. There is no beingaware of these differences, points become an extremely confusing and, i suspect, manygive increase on this subject.

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A qualitative expertise of magnetics include the followingten statements:

1. Phibìc magnetic poles point north, southmagnetic poles point south. 2. Like poles repel, unlike poles attract. 3. Magnetic forces attract only magnetic materials. A. Magnetic materials incorporate theelements iron, nickel, cobalt. 4. Magnetic pressures act at a distance. 5. If magnetized, temporary magnets (a item of iron) actlike permanent magnets. 6. A coil that wire v an electric existing flowing through itbecomes an electromagnet. 7. Putting iron inside a current-carrying coil rises thestrength of the electromagnet. 8. A an altering magnetic field induces an electric present in aconductor. A. The finest electrical conductors aresilver, copper, gold, aluminum (in the order). 9. A charged particle experiences no force when movingparallel come a magnetic field, but when that is relocating perpendicular to the fieldit experience a force perpendicular to both the field and the direction ofmotion. 10. A current-carrying wire in a perpendicular magnetic fieldexperiences a pressure in a direction perpendicular to both the wire and the field.

The very first four statements assist to explain how a compass works,but in order to recognize a lot larger team of phenomena using electromagnetssuch as motors, generators, transformers, door bells, speakers, headphones andactuators, we require a quantitative expertise that consist of the other sixstatements.

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a. Web links for this topic

http://en.wikipedia.org/wiki/Magnetism

http://en.wikipedia.org/wiki/Electric_current

http://en.wikipedia.org/wiki/Lines_of_force

http://en.wikipedia.org/wiki/Field_line

b. Present flow

We say that conventional existing flows native the + end of a battery come the - end. This is, that course, opposite to the electron flow, but was adopted as a result of Benjamin Franklin"s experiments. Part textbooks talk about electron flow that is from the - end of a battery come the + end. This deserve to be really confusing as soon as looking in ~ diagrams in that book since they then talk around left-hand rules rather of right-hand rules, and other things. On this net site, and in most college textbooks, conventional present is supplied where an arrowhead shows the existing flow indigenous + to -.Check the preface of a textbook you may be reading, to view what conventions the author is using. I"ve no purchased some publications if they have a various convention than what is gift here.

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c. Present into and also out-of a cross-sectional check out of a wire

In stimulate to show the direction of present flow, when looking at a cross ar of a wire, a "cross" (or "X") and a "dot" room used. A "cross" indicates the current is going into the page, as though you to be watching the fletching (feathers) of an arrow as the travels far from you. A "dot" indicates the present is coming the end of the page, together though you were watching the suggest of an arrowhead as the comes toward you! (Be sure to duck!)

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d. Magnetic flux flow

We say the magnetic currently of flux circulation from the north pole come the south pole outside of a magnet. Inside the magnet, the magnetic lines circulation from the southern pole wherein they gone into the magnet, come the north pole whereby they will leave the magnet. This is just a convention through which designers have agreed upon. Over there isn"t other physical that determines this, together is the case where electrons physically relocate from the - end of a battery come the + finish of a battery. However, one requirements to be consistent in order to recognize how tools using magnetic areas will behave. The Right-Hand-Rule and Left-Hand-Rule only works once currents and also fields space going in the directions we have predefined.

There are some who choose to think of the magnetic ar as flow from a positive resource to a an unfavorable source. This is an incorrect check out of how magnetic areas behave. Reasoning of a positive finish or an unfavorable end the a magnet isn"t horrible, however why not use the requirements that the magnet manufacturers use? rather say that the finish of the magnet the points toward the phibìc pole that the earth (in the Arctic), is yes, really a southern magnetic pole (saying over there is a phibìc magnetic pole located in the Arctic). Once these straightforward conventions are swapped around, we cannot completely understand what one is make the efforts to do without a special thesaurus to analyze their an individual conventions right into the normally embraced conventions.

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e. Magnetic field lines

Magnetic ar lines seen in drawings or computer plots are an help to visualize the magneticfield. They space not real yet are very useful! once using magnetic ar lines, note that they room closedpaths, choose rubber-bands laid out. Castle don"t cross each other, nor do theystart at some point and finish at another point. Every one constantly loops ago ontoitself.

We have these six simple rules because that magnetic ar lines: i) Magnetic field lines are consistent and will certainly always type closed loops. ii) Magnetic field lines will never ever cross one another. iii) Parallel magnetic field lines travel in the exact same direction defeat oneanother. Parallel magnetic field lines traveling in opposite directions tendto unite v each other and type into single lines traveling in a directiondetermined by the magnetic poles developing the ar lines. iv) Magnetic field lines often tend to shorten themselves. Therefore, the magnetic ar lines existing in between two unequal poles cause the poles to be pulledtogether. v) Magnetic field lines pass with all materials, both magnetic andnonmagnetic. Type I superconductors would be an exception to this. vi) Magnetic field lines constantly enter or leaving a magnetic product at rightangles to the surface.