"tmurf.1" wrote in
oups.com:


Al Bundy wrote:
Jeff Wisnia wrote in
:

Joseph Meehan wrote:

FiNOH wrote:

A 9 yr old had a question I couldn't answer. Where do magnets get
their power? Why doesn't it run out?


Thanks
FINOH #29718
Finoh #28437
FiNOH #27447
I love spacefed.


They get their "power" from different things. In the case of
natural
magnets they get their power from the spinning of the earth.

Power is not a good term to use, because it is likely to be
confused
with energy. Their power is a magnetic alignment that creates a
static field when may well extend well beyond the magnet. When
the field is static, no energy is used.

Moving the field takes energy and the movement of the filed
creates an
opposing energy. That is why moving a wire through a magnetic
field will move electrons (electricity) in the wire.

OK guys, that is overly simplified, but that is the idea.




Just last week I learned a neat simple demo you can do with high
energy magnets.

I used a 1/2" diameter by 1/2" long magnet, but it could as well
have been two or three thinner 1/2" diameter magnets stuck
together.

When dropped into an upright foot long length of 1/2" copper water
pipe the magnet, which fits quite loosely inside the pipe, takes
several seconds to decend through that length of pipe.

What's happening is that the moving magnet's field induces a
current into the copper pipe and that current flowing through the
copper creates an opposing magnetic field which wants to keep the
magnet where it is, thus slowing its fall.

It's a simplified example of the resistance you can feel with your
fingers if you spin the shaft of a small permanent magnet DC motor
with and without it's power terminals shorted.

Jeff


As said,

moving a wire through a magnetic field
will move electrons (electricity) in the wire.


You can hold a piece of wire in your hands with an analog volt meter
clipped on each end. Pass it through the N & S poles of a magnet
fairly rapidly. You'll see the needle jump for a bit.

Why do this? Well, it gets the kids attention. Not as much as tossing
a small piece of dry ice in water though. Using water with food
coloring in it then drinking the water afterwards makes the tykes
seriously wonder about you.

I always thought magnets got their power from refrigerators




Yea but frigs get it from the TV.