sci.physics.electromag

"Timo A. Nieminen" wrote in message
news:Pine.WNT.4.64.0803120539090.1476@serene.st...
| On Mon, 10 Mar 2008, FrediFizzx wrote:
|
| > "Timo Nieminen" wrote:
| >
| >> That said, "changing E causes B" and vice versa is a common just-so
story
| >> in introductory textbooks. I wonder why?
| >
| > It probably comes from the purely experimental situations of
demonstration.
| > Quoting Halliday and Resnick in "Physics"; "A bar magnet, thrust through
a
| > closed loop of wire, will set up a current in the loop." And similar
for a
| > current in the wire sets up a magnetic field near the wire. But note
that
| > they say "current" and not E field. Clearly, thrusting the magnet
through the
| > loop *caused* the current in the wire. But in other places they use the
term
| > "induces" instead of causes.
|
| Which goes to show that it isn't necessary to talk about "E causes B"

CHANGING E causes B - sheesh.

Position does not cause a relaxed spring to compress and exert a force
opposing the position, but changing position causes a spring to compress
and exert a force opposing the motion.