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| | Magnetic Fields |
 | | A magnetized bar has its power concentrated at two ends, its poles; they are known as its north (N) and south (S) poles, because if the bar is hung by its middle from a string, its N end tends to point northwards and its S end southwards. |
 | | The Earth's own magnetic powers arise deep in its interior, and temperatures there are too high for iron magnets, which lose all their power when heated to a red glow. |
 | | In fact, some of the world's strongest magnets contain no iron, because the added benefit of iron inside an electromagnet has a definite limit, whereas the strength of the magnetic force produced directly by an electric current is only limited by engineering considerations. |
| www-istp.gsfc.nasa.gov /Education/wmfield.html (696 words) |
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