Magnetic Suspension: Calculating I2

[Angie K.]

Homework Statement

[/B]

A long horizontal wire carries a current of I1 = 48.1 A. A second wire, made of 2.5-mm-diameter copper wire and parallel to the first but a distance d = 14.9 cm below it, is held in suspension magnetically. What is the current I2 in the second wire? (Enter a positive value if I2 is to the right, negative if it's to the left.)

Homework Equations

B=mu0/2pi*(I)/r

The Attempt at a Solution

I am not sure how to calculate I (current) without knowing the B (magnetic field) .

Can I use the equation from above to figure out the magnetic fields with plugging in different r values? If so, then would I just set them equal to find the other current?

 

[BvU]

Hello there,

Sort of. You can use your equation to calculate the magnetic field at the position of the lower wire.
Once you have that, you will need another equation to deal with the suspension part.
I expect you can write a force balance for the two forces working on the lower wire ?

 

[Angie K.]

Hello there,

Sort of. You can use your equation to calculate the magnetic field at the position of the lower wire.
Once you have that, you will need another equation to deal with the suspension part.
I expect you can write a force balance for the two forces working on the lower wire ?

By force balance, do you mean F=I*L*B ?

 

[BvU]

That is one force, yes.

[edit]
Now: you know B (I hope). And what about F ? I₂ is to be found, so we must invent something for L. Any ideas ?

 

[Raghav Gupta]

Hello BvU once again and Angie

Homework Statement

[/B]

A long horizontal wire carries a current of I1 = 48.1 A. A second wire, made of 2.5-mm-diameter copper wire and parallel to the first but a distance d = 14.9 cm below it, is held in suspension magnetically. What is the current I2 in the second wire? (Enter a positive value if I2 is to the right, negative if it's to the left.)

Homework Equations

B=mu0/2pi*(I)/r

The Attempt at a Solution

I am not sure how to calculate I (current) without knowing the B (magnetic field) .

Can I use the equation from above to figure out the magnetic fields with plugging in different r values? If so, then would I just set them equal to find the other current?

That red equation is mu0i/2pi r or $\frac{\mu_0i}{2πr}$
I think you had a typo there and BvU was pointing it correct.

 

[BvU]

Hello Raghav !

RG: I did no such thing. And I don't think there was reason to do so.

AK: No reason for alarm: just written a bit awkward, so that a casual reader is easily wrong-footed.

I am sure you meant B = mu₀/(2pi) * I / r

As you can see, RG's way of typesetting with LaTeX is much clearer and unambiguous. Worth looking into how to do that ! (see guidelines)