Magnetism

[Albert]

What does this mean?

Recall the sideways force on a horizontal wire carrying current in a
vertical magnetic field (direction NOT required; only need to know
that force is perpendicular to wire).

Could someone explain or rephrase this question? How is a magnetic
field 'vertical' if it loops around from north to south?

Albert

[Jeffrey Turner]

While all lines of a magnetic field form closed loops, for a small
section they can be approximated as straight. Think of the surface of a
lake, which curves with the Earth but we think of as flat. If you have
a vertical section of the magnetic field, and a horizontal wire:

| | | | | | |
| | | | | | | <-magnetic field lines
| | | | | | |
------------------------- <-wire
| | | | | | |
| | | | | | |
| | | | | | |

The force on the wire will be into or out of the plane of your monitor,
depending on the direction of the magnetic field and the direction of
current in the wire.

--Jeff

--
"The power of the Executive to cast a man into prison without
formulating any charge known to the law, and particularly to
deny him the judgment of his peers, is in the highest degree
odious and is the foundation of all totalitarian government
whether Nazi or Communist."

- Winston Churchill, Nov. 21, 1943

[Albert]

Cool, but why?

[Jeffrey Turner]

Albert wrote:
> On Mar 2, 1:49 am, Jeffrey Turner <jtur...@localnet.com> wrote:
>
>>Albert wrote:
>>
>>>What does this mean?
>>
>>>Recall the sideways force on a horizontal wire carrying current in a
>>>vertical magnetic field (direction NOT required; only need to know
>>>that force is perpendicular to wire).
>>
>>>Could someone explain or rephrase this question? How is a magnetic
>>>field 'vertical' if it loops around from north to south?
>>
>>While all lines of a magnetic field form closed loops, for a small
>>section they can be approximated as straight. Think of the surface of a
>>lake, which curves with the Earth but we think of as flat. If you have
>>a vertical section of the magnetic field, and a horizontal wire:
>>
>>| | | | | | |
>>| | | | | | | <-magnetic field lines
>>| | | | | | |
>>------------------------- <-wire
>>| | | | | | |
>>| | | | | | |
>>| | | | | | |
>>
>>The force on the wire will be into or out of the plane of your monitor,
>>depending on the direction of the magnetic field and the direction of
>>current in the wire.
>

> Cool, but why?

Because that's how magnetic fields work. A moving charge (the current)
in a magnetic field gets pushed sideways. If you had an electron beam,
instead of a wire, and a big enough magnetic field, the electrons would
move in a circle. If you take your right hand and point your fingers in
the direction of the magnetic field and your thumb in the direction of
the current then your palm will push in the direction of the force on