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What to do when you run out of copper.
SkyMan
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We all know about how the composition of the penny and the nickel were changed during World War II. I read an interesting fact in a book tonight. To build The Bomb, Ernest Lawrence of the U of CA. worked on electromagnetic separation of U-235. Lawrence calculated that he would need the world's largest magnets, each 250 feet long. It would take thousands of miles of copper wire to wind the coils of these mammoth magnets, but war-industry demand for copper had all but exhausted the US supply. He thought about what do do and came up with an out of the box suggestion... use silver... as he said, "It is an excellent conductor of electricity". Needless to say, the Treasury had a cow when informed that Lawrence needed 6,000 TONS of silver. Making a long story short, given the priority nature of the Bomb, eventually the Manhattan project borrowed a total of 14,000 TONS of silver (out of roughly 86,000 tons of total Treasury supply), promising to return it 6 months after the war ended. When the war was over the Treasury got back all but 4.9 tons... or 0.035 of 1% of it's silver. So silver was not just used in the silver nickels of WWII, but in another even more critical aspect of the war.
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I thought your post was going to address the current nickels that are 75% copper, even though copper has been taken out of pennies....
And Silver is also a slightly better conductor than copper. --Jerry
<< <i>... What was the book you read?... >>
Time/Life books, "The Fall of Japan".
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<< <i>
<< <i>... What was the book you read?... >>
Time/Life books, "The Fall of Japan". >>
Thanks, I'll try to pick that up.
--Jerry
Worry is the interest you pay on a debt you may not owe.
"Paper money eventually returns to its intrinsic value---zero."----Voltaire
"Everything you say should be true, but not everything true should be said."----Voltaire
My brother showed me an interesting experiment with a magnet and copper conduit.
He had a round magnet and dropped it on the ground. He had me count. It took one second to drop five feet.
He then inserted this magnet into a four foot piece of copper conduit, held the copper a foot off the ground and dropped the magnet through it, starting from the same height as the first time he let it "free fall". .
I counted " one, one thousand, ... two one thousand, three one thousand"... and by the time I hit "11", it fell through the bottom and hit the floor.
Why did it take 11 seconds for a round magnet to drop through a piece of copper tubing ? There was plenty of gap between the walls of the tubing and the magnet. Copper is not magnetic.
Please explain
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<< <i>What to do when you run out of copper.
My brother showed me an interesting experiment with a magnet and copper conduit.
He had a round magnet and dropped it on the ground. He had me count. It took one second to drop five feet.
He then inserted this magnet into a four foot piece of copper conduit, held the copper a foot off the ground and dropped the magnet through it, starting from the same height as the first time he let it "free fall". .
I counted " one, one thousand, ... two one thousand, three one thousand"... and by the time I hit "11", it fell through the bottom and hit the floor.
Why did it take 11 seconds for a round magnet to drop through a piece of copper tubing ? There was plenty of gap between the walls of the tubing and the magnet. Copper is not magnetic.
Please explain >>
This is an excellent demonstration of Lenz's law and eddy currents. When a magnet is dropped through a vertical copper pipe, it falls much slower than a steel ball would. Its rate of fall quickly reaches a terminal velocity and it takes much longer for it to fall out of the other end than a steel ball would take.
Lenz's law is a basic law in electromagnetic theory for determining the direction of flow of induced currents.
According to Lenz's law, when a current is caused to flow in an electrical conductor by a change in the external magnetic field surrounding the conductor, the direction of flow of the current is such as to produce a magnetic field opposing the original change in the external magnetic field.
This explains the behavior of magnets and conductors when one is moving relative to the other. For example, when a conductor is moving across a magnetic field, a current is caused to circulate in the conductor producing a magnetic field which tries to stop the conductor from moving.
I'm not at all disagreeing with billet7's explanation, just giving it another way.
--Jerry
All the coppers available in town will arrive in just a few minutes!
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How about the US coinage of Dutch colonies and Australian silver coins. I think we loaned silver to the British for their coins. They paid it back by removing all silver from coins in 1946 (excluding the small amount of Maundy money).
They withdrew all the old silver coins, so certainly would have had enough to pay us back. This is just one of many random facts floating around in my memory and I can't prove it or fill in the details. It will be a mess when senility strikes me. I think the late writings of Walter Breen showed some such similiar confusion.