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# Physics/Magnetic generators

Question
Hi, I'm studying how copper induction coils work in magnet power generators.  I was wondering, if the Gauss of the magnet is stronger, does it create more charge than a weaker Gauss, and should the copper coil's thickness be equal to the length of the magnet's pole lines?  Also does the gauge of the copper wire make a huge difference?

> if the Gauss of the magnet is stronger,
> does it create more charge than a weaker Gauss

First thing to understand about the generation of electrical power through magnets is the basic law: the electromotive force (ie, the voltage) created around a loop of wire depends on the degree CHANGE in the magnetic field (aka the 'B-field') going through that loop*. If you understand that principle, everything that follows is relatively easy; if you fail to do so, everything that follows is difficult.

The situation is best imagined in the image on the left:
http://digilander.libero.it/mfinotes/images/eminduction/Image55.gif
with the magnetic field going through the loop of wire. Note that, in this case, the B-field is perpendicular to the circle caused by the loop. As noted above, a CHANGE in the B-field through that loop will case a voltage around that loop -- which is how electrical power is generated. The key is how to create a change in the B-field through that loop. One way is to keep the loop unchanged, but to change the B-field itself. Far more practical is to rotate the loop. Note that, if the loop is rotated by 90 degrees with the B-field in the same direction (image on the right), no magnetic field goes through the loop. Thus, the B-field through goes from full strength to zero -- a CHANGE in the B-field through the loop, causing a voltage around the loop of wire.

If you fail to understand the previous paragraph, I can't help you any further.

Okay, so now you DO understand the principle. Note that, if the size of the B-field -- measured in gauss -- is stronger, rotating the loop causes the loop to go from a larger number to zero. Assuming the rotation speed is the same, this is a larger CHANGE, and thus causes a larger voltage within the loop. There is not more CHARGE, just a larger voltage. So, stronger gauss means more volts, but not more charge.

> does the gauge of the copper wire make a huge difference?

Not in the size of the voltage created. However, a generator will need to have copper wire strong enough to withstand the current created without overheating.

> should the copper coil's thickness be equal to the length of the magnet's pole lines?

This makes no difference. Just keep thinking of the primary law of voltage induction.

* More precisely, it's the magnetic FLUX through the loop, but we'll talk about the B-field for simplicity.
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I can help with understanding physics that does not involve eggs. I will NOT help with academic or professional questions, which are NOT limited only to homework. Please do not waste your time by asking a question that comes out of ANY kind of academic, professional, or business matters.

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Have been fascinated by physical laws ever since I learned, at age seven, that magnets work under water. My study continued through college and has not ceased even after I retired.

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B.A. in Physics (with honors) from University of California at Berkeley.M.A. in Physics (with honors) from University of Texas Austin.