A coil of 25 turns of wire is suspended by a thread

[Astraithious]

Homework Statement

A coil of 25 turns of wire is suspended by a thread. When a current flows through the coil, the tension in the thread is reduced by 4.0 ´10-2N.
http://members.shaw.ca/barry-barclay/Self-Tests/test11/Magnet20.gif

Homework Equations

F=IBL
B=nμI[/B]

The Attempt at a Solution

I have been driving myself nuts with this question haha but here is my attempt.

The force against gravity has to come from the current so I tried

0.04 = I (0.065)(0.15)
I = 4.1a, which is incorrect

then I tried combining the two

to get
I=√F/Nμ

but that left me with 35.68

So I am at a loss as to how to go about this , any help would be great! or any formulas I am missing. I have not done calc yet this is all supposed to be simple algebra however this process for this particular question eludes me and it is the last of the set of 190 , I want it done! haha

Correct answer is .16 amps I know it has to go counterclockwise for the force to be pushing up

 

[TSny]

1
The force against gravity has to come from the current so I tried

0.04 = I (0.065)(0.15)
I = 4.1a, which is incorrect

Did you take into account that there are 25 wraps of wire?

 

[Astraithious]

Haha I did however I did 0.04 = I 0.065x25x0.15, not 0.04 = I 0.065x(25x0.15)

Thank you so much lol, i knew it was simple but it was killing my soul with frustration