Well, I got several answers to this one:
To repeat the riddle:
Here's a little test to see if you're a real SI geek!
What does the following expression represent:
80 ZA-m^2
Hint: This is roughly the strength of the earth's magnetic field.
Write out the answer in words.
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ANSWERS:
At 13:14 2000-11-10 -0800, Marcus (Ma Be) wrote:
>eighty zettaamperes per square meter, or
>80 times 10 to minus 21 amperes per square meter
That was close, though the sign of the exponent is off (zetta Z is e21,
zepto z is e-21). This must have been a typo on Marcus' part.
At 16:30 2000-11-10 -0500, [EMAIL PROTECTED] wrote:
>an incorrect unit.
No, it is legit!
At 13:27 2000-11-10 -0800, Bill Potts wrote:
>Really? I thought magnetic field strength was expressed in amperes per
>meter.
>
>However, I've a feeling the words you want us to come up with start with
>"four score" rather than "eighty."
>
>"Four score and zettamp ares ago," possibly?
Well, to get technical, my sister the paleomagnetist puts it this way: "It
is the magnetic moment of the best fitting geocentric dipole (bar
magnetic) that would give rise to the observed field intensities a the
surface. Here it is about 40 micro Tesla." So I guess it's a moment,
rather than a field strength, bill. I stand corrected. To boil this down
into pure SI, the Tesla is a Wb/m^2, and a Weber is a V-s, a Volt is a W/A,
and a Watt is a J/s, the joule is a N-m, and a Newton is a kg-m/s^2. So, by
calculations, the Tesla is a kg/A-s^2. Whew!
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THE ANSWER, by the way:
80 ZA-m^2 is eighty zettaamperes per square meter.
Not too often you get to use zetta! My sister had asked me what the prefix
should be, knowing that I am an SI nut, and we had fun with this. It could
also be
0.08 YA-m^2 (0.08 yottaamperes per square meter).
We figured e27 must be "lotta".
- John
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