On May 12, 8:43 am, "Kevin G. Rhoads" wrote:
If we ever build a Beanstalk (tethered mass in geosynchronous
equatorial orbit) will the stalk carry a current from "cutting" the
Earth's field as it orbits?

If conductive, perhaps -- remember B fields, like motion, are expressed
in vectors, so the cross product can be zero even if both terms are not
(they only need be parallel).

It was a "trick" question. The Earth's field is generated somewhat
differently from that of an ordinary magnet; the angular velocity of
the conductive fluid within the Earth that generates its field is not
directly tied to the angular velocity of the surface (note that the
spin and magnetic poles of the Earth are not co-located and their
relationship changes over time).

So yes, a (conductive) Beanstalk will definitely carry a current.

Benj may feel cheated; I suggest he research the Homopolar Generator
and variants.


Mark L. Fergerson