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Metal alloys of some coins used as testing standards
1 Euro "Yellow part is 75% copper, 20% zinc, 5% nickel"
"White part is 75% copper, 25% nickel"
50 Cents 89% copper
20 Cents 89% copper
"1,2,5 Cents" copper clad steel
US$ 25 Cents 75% copper /25% nickel TC about 200us
US$ 10 Cents 75% copper /25% nickel TC about 80us
US$ 5 Cents 92% copper/8% nickel TC about 15us
US$ 1 Cent 97.5% zinc/2.5% copper TC about 70us
The TC of a US$ 10c which is very much smaller in size, thickness as well as diameter, is much longer than the TC of a US$ 1c. This is evident with the copper clad 1c and even more with the old full copper coin.
The difference lies in the alloy.
What about the orientation of the coins within the coil field?
We know that the signal response amplitude is very much less for a vertical coin than for a horizontal coin. But, what about the TC? is it shorter?
How do the eddy currents circulate in the vertical coin?
The smaller incidence of field lines in the vertical coin explain the lesser signal amplitude.
Now, if we look at the 1 Euro coins, it gets even much more complicated. 2 different alloys and the one in a ring form and the other one in a thick disk form and both intimately connected.
A real nightmare for the eddy currents.
Gold jewelry comes in a myriad of shapes and a myriad of alloys. Undecipherable.
Metal alloys of some coins used as testing standards
1 Euro "Yellow part is 75% copper, 20% zinc, 5% nickel"
"White part is 75% copper, 25% nickel"
50 Cents 89% copper
20 Cents 89% copper
"1,2,5 Cents" copper clad steel
US$ 25 Cents 75% copper /25% nickel TC about 200us
US$ 10 Cents 75% copper /25% nickel TC about 80us
US$ 5 Cents 92% copper/8% nickel TC about 15us
US$ 1 Cent 97.5% zinc/2.5% copper TC about 70us
The TC of a US$ 10c which is very much smaller in size, thickness as well as diameter, is much longer than the TC of a US$ 1c. This is evident with the copper clad 1c and even more with the old full copper coin.
The difference lies in the alloy.
What about the orientation of the coins within the coil field?
We know that the signal response amplitude is very much less for a vertical coin than for a horizontal coin. But, what about the TC? is it shorter?
How do the eddy currents circulate in the vertical coin?
The smaller incidence of field lines in the vertical coin explain the lesser signal amplitude.
Now, if we look at the 1 Euro coins, it gets even much more complicated. 2 different alloys and the one in a ring form and the other one in a thick disk form and both intimately connected.
A real nightmare for the eddy currents.
Gold jewelry comes in a myriad of shapes and a myriad of alloys. Undecipherable.
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