# Force on Current Loop

## Homework Statement

Here is the problem and the picture that goes along with it. I am really stuck because our teacher never explained a problem like this to us before. Any help is appreciated!! THank you so much

http://a2.sphotos.ak.fbcdn.net/hphotos-ak-ash4/229022_113377112081455_100002275016913_125327_6984938_n.jpg [Broken]

## Homework Equations

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Here are the equations that I was given

http://a2.sphotos.ak.fbcdn.net/hphotos-ak-snc6/223417_113388105413689_100002275016913_125390_5418139_n.jpg [Broken]

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$$F = BI l \sin\theta$$

$$B_{wire}=\frac{\mu_0I}{2\pi r}$$
to find out the force per unit length b/w two infinite parallel wires carrying currents $$I_1, I_2$$. Can you do that?

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THank you so much!!

Sorry I just realized... irdg what you meant
@praharmitra...

sorry can you explain a little bit more

Ok, what I want you to do is find the force per unit length b/w a pair of infinite wires separated at a distance r. Here's what you do.

You have one wire carrying current $I_1$. What magnetic field does it produce at a distance r from itself?

Now the second wire carrying current $I_2$, is in the presence of the magnetic field you calculated above. Therefore, what is the force per unit length on this wire?

Would you do it like this:??

Fnet = Fnear - Ffar = (µoI1I2)(ℓnear)/(2πdnear) - (µoI1I2)(ℓfar)/(2πdfar) = (µoI1I2ℓ)/(2π) * (1/dnear - 1/dfar) = [(4π x 10-7T·m/A) (2A)(3A)(6m)]/(2π) * [1/1 - 1/3] = 4.74 x 10-5N away from the wire

doest that make sense? llol

Thank you so much for all the help guys!

yes, that is correct yes.