# Help with magnetism

#### laker88116

A wire 36m long carries a current of 22 A from east to west. If the maximum magnetic force on the wire at this point is downward (toward the Earth) and has a magnitude of 4.0E-2N, find the magnitude and direction of the magnetic field at this location.

I have no clue where to start. What does force have to do with it, the given force, I know you're trying to find force.

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#### jdavel

laker,

What makes you think you're supposed to find a force?

#### laker88116

well it says find the magnitude and its location, magnetic fields have forces of magnetism

#### laker88116

hence "magnetic force on the wire at this point is downward (toward the Earth) and has a magnitude of 4.0E-2N"

#### jdavel

laker,

"magnetic fields have forces of magnetism"

Not really! You need something besides a magnetic field to have a force. What is it?

#### vincentchan

the Force is related to the current and the B field by:
F=LIxB....
L is the length of the wire
I is the currect
B is the B field

the bold letter means vector in my notation...

#### laker88116

thanks i got it now

#### laker88116

jdavel, your not helping, your complicating the situation, i know what im talking about more then you obviously cause you had no clue where start you just interrogated me

#### jdavel

laker,

Sorry. I was just trying to get you to think about how to solve the problem for yourself. Fortunately for you vincentchan made that unnecesary by handing you the answer.

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