Make a magnetic metal bar?
454527
wrap the bar in insulated copper wire, preferably solid core, keeping the wraps smooth and close together, and wrap three layers deep- when you reach the end of the first layer just wrap back towards the end you started at, same thing on third layer- them hook a DC power supply to the ends of the wire wrap, and let the thing run for 3-4 days (make sure when you hook it up that it doesn't heat much if any) pretty soon you've got a magnet.
612302
You could build a set of fluid armor as seen in the Matrix movie.\n\nA simple magnetorheological fluid can be home-made out of small magnetic particles mixed with mineral or vegetable oil. Iron filings do not work well; they are too big. Good sources for small magnetic particles are:\n\n* magnetic inspection powder from welding shops\n* particles from burned steel wool (after mortar and pestle)\n* particles scraped from the surface of video tapes\n* particles "mined" from sand with a plastic bag and a magnet (see external links)\n\nThese fluids are not very stable, however. The particles will tend to clump and the fluid properties will be lost quickly. Fluids created for professional purposes use emulsifiers to suspend very small oily (octane or kerosene) magnetic particles in water. The particles are very fine; less than a micrometre in diameter.
687020
yes, just take a conical mold, pour in some molten iron, and keep it in a magnetic field as it cools. north and sout poles WILL be opposite sides, but it could have a weird overall field.
985642
You try what the first poster suggests, but it isn't likely to work well. Besides the danger mentioned of doing damage to the equipment, you will have one of these problems that will prevent the result you want:\n1) the electromagnet won't be strong enough to have any demagnetizing effect at all, \nor,\n2) the electromagnet will completely demagnetize the permanent magnet.\n\nUsually magnetic catches consist of a flat steel plate that seats against two poles of the magnet. A better solution is to put a few layers of tape on the steel plate so that it does not come into contact with the pole pieces. Depending on the kinds of tape you have around, one layer might be enough.\nMagnetic force falls off very rapidly as you separate the surfaces.
883128
Use a magnet. Iron is attracted to it, lead is not.
105221
Well, the easiest way is to get some wire, wrap it around a iron/steel rod, and apply a current to the wire.\n\nTo get an electromagnet to have a lifting capacity that you specified, it will require a little more engineering work.  Trying to stay in the most basic terms, the power of your magnet will depend on how much current you put through the wire, how many turns you have around the iron rod, and something called the magnetic permeability of the iron rod.  Now there's some trade-offs with all of these factors.  More turns increases the magnet flux (strength), but requires more wire and increases the resistance.  More resistance means that you will need more current to counteract this problem.  Treating your electromagnet strictly as a resistor (which it is not), by following Ohm's law, you increase the current by increasing the voltage.   Too much current and you may end up melting your wire.   You want to keep the wire as small as possible so that you can get the turns as close as possible to your iron rod, but smaller wire has a higher resistance and lower current carrying capability.\n\nIt's a matter of balancing a lot of equations to get the best combination.  Your best bet is a little trial and error.
744142
Attract..mmm...TRY A MAGNET !!
306003
By bar I assume you mean reinforcing steel. Each size has a bend diameter. Go to the ASTM and pull up the chart. Next a hydraulic press is best to provide the action.
76483
cobalt can be used just about anywhere iron could. the primary place would probably use in magnets
354803
You can take a magnetizable substance and change the polarity with electric coil or by rubbing another magnet in the same direction against the substance.  This will allign the mollecules changing the polarity of the object.
85373
Magnetic force........
417868
Your best bet would be to use water and make a salt water solution.  Using a magnet would work well unless you had a lot of iron fillings together and they were under some salt and all of them were pulled out of the mixture.  Then you would still have salt with the iron.  \n\nMake a aqueous(with water) solution, filter, and allow the water to evaporate.
1008527
It only can be a magnet when it the metal  can be a magnet.\nKeep it near a magnet. (The metal of a loudspeaker)
1142672
A few magnets will do the trick.... even a really large scientific one.
243953
The magnetic bars in most toys are coated with plastic.  The plastic is relatively inert in the stomach acid and passes through to the intestines.\n\nTwo magnets in the intestines can attract each other and cause either a perforation (hole in the intestines that leads to a severe infection) or an obstruction/blockage.  Either requires surgery to correct.
1044939
put one of those magnetic signs of your car
140684
I guess it can be magnetized. I don't think there would be any problem even if its in the form of a moebus strip, or any form at all. Anyway I am curious for other answers.