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I think I know the answer to this already but I can't seem to find this on Google. The keywords are all far too ambiguous apparently.

I want to create a electrical flow with a magnet passing through a cylinder wrapped with copper wire. Pretty basic. I want to increase the voltage output.

My theory is that if I wound the copper tighter, decreased the width between them and increase the copper on the cylinder that I will get a higher voltage. I haven't tried it yet because I haven't bought the equipment. I am trying to plan it all out before I purchase anything. Is my assumption correct?

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  • \$\begingroup\$ Have you tried googling - pass magnet through coil voltage? \$\endgroup\$ – George White Jan 9 '14 at 0:06
  • \$\begingroup\$ Have you tried googling that? Is this a cryptic passive aggressive way of telling me these are the correct technical keywords I need to find my answer? \$\endgroup\$ – Anthony Russell Jan 9 '14 at 0:08
  • \$\begingroup\$ Of course I would not post that in an answer. As a comment I was trying to "help you learn to fish" rather than handing you the fish. The listing that was at the top of the list when I did that search was hyperphysics.phy-astr.gsu.edu/hbase/electric/farlaw.html that happened to be a good tutorial on the subject. \$\endgroup\$ – George White Jan 9 '14 at 0:18
  • \$\begingroup\$ I know how to research. As I clearly indicated in my post I didn't know which keywords I needed. Thank you for providing the correct Keywords that led me to my answer. If you post it as an answer along with Faraday's Law I will check mark and upvote. \$\endgroup\$ – Anthony Russell Jan 9 '14 at 0:22
  • \$\begingroup\$ Note that a short magnet passing through a long cylinder-coil will not produce a current except when the magnet is entering or exiting. Two poles inside the coil, equals zero coupling, zero EMF. Best would be a short thick coil, then use just one end of a very long magnet. Axially wiggle either the magnet-pole or the entire coil. \$\endgroup\$ – wbeaty Apr 14 '16 at 5:41
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By Faraday's Law the voltage is proportional to the number of windings and the rate of the change in the magnetic field. So you can add windings, as you mentioned, move the magnet faster or use a stronger magnet at the same rate to increase the voltage. I would look at http://hyperphysics.phy-astr.gsu.edu/hbase/electric/farlaw.html and http://www.electronics-tutorials.ws/electromagnetism/electromagnetic-induction.html for an explanation of Faraday's Law.

From wikipedia: enter image description here

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I want to add that if you are using off the shelf components and they are not generating the voltage you need, a simple boost converter can be used. Not only will it step up the voltage to something you need, it will also smooth out the varying voltages from the generator.

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

https://www.sparkfun.com/products/10968

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but if number of turns is increased resistance will be more and less induced emf is produced .

we know L= Kn*nAl which means self inductance of coil is directly propotional to square of n ;area of cross section A ;length of coil l

in order to have greater output EITHER 'A' CAN BE INCREASED ORMORE POWERFUL CAN BE USED . IF V BE THE VELOCITY OF MAGNET IN THE COIL THEN INDUCED EMF PRODUCED IN THE COIL IS e=-BIV

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Rotating the magnet (where the poles 'pass through?') Or sliding a magnet-rod through a cylinder-coil?

#1 is to add more turns. #2 is to add more turns of fine wire, so the added turns aren't lifted far from the magnet.

Also, for linear-moving magnet (not rotation,) note that a long coil and short stubby magnet won't work very well. If both magnet poles are inside the coil at the same time, then their effects cancel. Even if both poles are close together while the coil diameter is wider ...same problem. To get maximum output volts, just one pole should pass through the coil, followed by just the other pole. The cylinder-coil needs to be the same length as the magnet, or shorter.

Are you forcing the magnet to move, or instead just letting it slide under its own weight+inertia? If forcing the magnet via attached shaft, then you can make the fields much stronger by adding iron parts as a stator, a flux-concentrator. But this also increases the required force applied to the sliding magnet. Iron parts will hang up a freely-sliding magnet. But for a "pushed piston" setup, the piston force can be huge; much larger than the "cogging" or "sticking" effect on the magnet caused by nearby iron.

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One additional thing I want to add to the seleted answer is the following paragraphs taken from this site

A Simple Generator would consist of a U-shaped magnet and a single loop of wire. The area around a magnet where its force can be felt is called a magnetic field. To help describe a magnetic field, we think of lines of force going out from the north pole of a magnet and returning into the magnet at its south pole. The stronger the magnet, the greater the number of lines of force. If you rotate the loop of wire between the poles of the magnet, the two sides of the loop "cut" the lines of force. This induces (generates) electricity in the loop.

In the first half of the turn, one side of the loop of wire cuts up through the lines of force. The other side cuts down. This makes the electricity flow in one direction through the loop. Halfway through the turn, the loop moves parallel to the lines of force. No lines of force are cut and no electricity is generated. In the second half of the turn, the side of the loop that was cutting upward cuts downward through the lines of force. The other side of the loop cuts upward. This makes the electricity induced in the loop flow in a direction opposite to the first half of the turn. At the bottom of the turn, the loop again moves parallel to the lines of force and no electricity is generated. For every complete turn, the voltage and current that are generated travel in one direction half the time, and in the opposite direction the other half of the time. Twice during each turn no current flows. The voltage and current are known as an alternating voltage and an alternating current. The voltage that a generator produces can be increased by increasing:

(1) the strength of the magnetic field (number of lines of force),

(2) the speed at which the loop rotates, or

(3) the number of loops of wire that cut the magnetic field.

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protected by Dave Tweed Jul 30 '18 at 13:57

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