Please describe electrical conduction and induction

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black008
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28 Mar 2013, 8:54 am

I am a visual learner. I been reading on electrical conduction and induction. I know it is a transfer of electrons. Can someone give me some real world examples. I think if I had some help visualizing it, I would be on my way.

Most things I have found thus far on the internet only restate what the author has already written or they use an electroscope. I realize one touches and one only gets close to an object. I know their is a transfer of electrons. But I am still missing something. I really want to increase my knowledge of electricity. This is all very new to me. Any help would be appreciated.


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ScrewyWabbit
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28 Mar 2013, 12:42 pm

From what I remember from school...

Electrical conduction is a property of a material by which it has the ability for electrons to flow freely through the material with relatively low resistance. This is because the electrons - especially the outer electrons, of the atoms or molecules are not tightly bound to the nucleus. This is true of metals (if you look in the periodic table, you'll see metals all have similar electron configurations). Of course, every material can conduct electricity IF there is enough electricity. Thick rubber gloves could protect you if you were working on a high voltage power line, for instance, but they probably won't do much good for you if they're struck by lightning.

Electrical induction is something else. Basically, you can cause the electrons in a material to start moving (flowing) - thus producing an electric current. You do this by moving the material through a magnetic field, such that the material and the magnetic field are oriented in the correct directions. The reason is that the electrons in the material will be attracted / repelled by the magnet, and especially in a good condutor like a metal, where the electrons can move around easily, the attraction / repulsion will force the electrons to start moving. Induction is what allows generators to work. Basically you move a coil of wire around a magnet (or rotate some magnets near the coils of wire) which causes the electrons in the wire to start moving and flowing.



Fogman
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28 Mar 2013, 1:08 pm

Electric Transformers are a good case study for both induction as well as reduction.

A transformer will either raise, or induce voltage, or lower voltage, much the same way that an auto trasmission reduces engine RPM to spin the transmission differential and therefor the wheels on your car. in (usually the first 3-4 gears) the transmission will be operating in reductive mode, due to the fact that it is reducing the engine RPM's to turn the wheels from a standing stop to about 35Mph. The next gear, (usually either gear 4 or 5) the spin ration on the engine and transmission is 1:1.

When you shift into overdrive ( either gear 5 or 6 in modern cars) you are using the transmission in induction mode because the ratio of spin may be .75:1. --The engine's RPM's are actually lower than the transmission's output RPM.

Conversely, the PSU in Tube amplification is inductive due to the fact that they accept input voltage ( North American 120VAC or Euro 220VAC) and boost output voltage to between 350- 700 or so volts before the power gets rectified to DC and smoothed by electrolytic filtering capacitors.

Neon sign transformers work much the same in that their transformer primary windings accept 120-240VAC while the secondary, (or inductive winding) outputs between 10-20Kv.


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NewDawn
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28 Mar 2013, 7:38 pm

Have you tried the free MIT course Electricity and Magnetism by Walter Lewin? Lewin has a very visual teaching style and comes up with lots of interesting real world examples.

http://ocw.mit.edu/courses/physics/8-02-electricity-and-magnetism-spring-2002/index.htm

He's doing the same course on EdX at the moment.

https://www.edx.org/courses/MITx/8.02x/2013_Spring/about



black008
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28 Mar 2013, 7:59 pm

Thanks is good. I looking at the videos now.


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