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JohnArcher10-Marble
10-Marble
April 13, 2021
Question

Mathcad Prime unit system

  • April 13, 2021
  • 1 reply
  • 1973 views

Why is Oe in the SI list?  The modern developed unit is H in A/m. 

1 reply

W
Werner_E25-Diamond I
25-Diamond I
April 13, 2021
@JohnArcher wrote:

Why is Oe in the SI list?  The modern developed unit is H in A/m. 

A/m is not ONE unit but a combination of two. So you won't find it in the unit list. You also won't find m/s when you look for speed units, but any speed will be automatically shown in m/s.

You can always type in A/m yourself as you like.

And results are displayed in A/m anyway. So I can't spot any problem.

J
JohnArcher10-MarbleAuthor
10-Marble
April 14, 2021
Thanks' for your prompt response. I was aware of tour answer, that is why I called A/m a developed unit. My point was that Oersted does not belong in a listing of SI Units. Mathcad11 had the same mixed problem. Perhaps Prime should rename its list.
My first usage was Mathcad4 on a 5.25inch floppy! The first computer that was just mine to use was a DEC PDP8I, using Focal, with 8k of real magnetic core, yards of punched paper tape and an ASR33 teletype, which I used to design RCA color tube deflection yokes. I was born in London in 1936, been a working engineer since 1956, and seen a few Unit System changes. Engineering challenge is still fun and learning never stops.
F
Fred_Kohlhepp23-Emerald I
23-Emerald I
April 14, 2021

According to Merriam-Webster:

Oeersted:  the unit of magnetic field strength in the centimeter-gram-second system.  First used in 1930.

 

According to Wikipedia (that you need to check):

The original motivation for the development of the SI was the diversity of units that had sprung up within the centimetre–gram–second (CGS) systems (specifically the inconsistency between the systems of electrostatic units and electromagnetic units) and the lack of coordination between the various disciplines that used them. The General Conference on Weights and Measures (French: Conférence générale des poids et mesures – CGPM), which was established by the Metre Convention of 1875, brought together many international organisations to establish the definitions and standards of a new system and to standardise the rules for writing and presenting measurements. The system was published in 1960 as a result of an initiative that began in 1948, so it is based on the metre–kilogram–second system of units (MKS) rather than any variant of the CGS.

 

So you are technically correct, Oersted is not SI.  Prime 4.0 Express with CGS unit specified.  (Built-in unit not specified?:

Fred_Kohlhepp_1-1618424777116.png

 

With MKS specified

Fred_Kohlhepp_2-1618424808120.png

And with USCS specified:

Fred_Kohlhepp_3-1618424948907.png

So Prime has issues with units.

 

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