Net force on rectangular circuit

[Alameen Damer]

Homework Statement

Homework Equations

Right hand rules

The Attempt at a Solution

Am i correct for a? I drew my interpretations of the magnetic field around each section.
For b) am i correct to think the internal net force in the rectangular wire is 0, and the only force acting on it is that of the long wire at the bottom. And if that is correct, which way is the net force acting on the rectangular loop?

 

[Titan97]

For part a, all your forces have to be in opposite direction.
F=i (L×B)
For the bottom part, L is along $-\hat i$ and B is along $\hat k$.
L×B is along $-\hat j$ or downwards.

 

[Alameen Damer]

Why are they in opposite directions? Does that not fit the right hand rule?

 

[rude man]

For b) am i correct to think the internal net force in the rectangular wire is 0, and the only force acting on it is that of the long wire at the bottom.

yes

And if that is correct, which way is the net force acting on the rectangular loop?

where is the B field stronger, nearer the long wire or farther away from it?

 

[Alameen Damer]

Near the long wire, then it must be acting downwards correct?

 

[rude man]

Near the long wire, then it must be acting downwards correct?

Since you previously showed that you could determine the direction I'm giving you a "Yes".

 

[Alameen Damer]

Ok, are the directions of the magnetic field around the rectangle wrong?

 

[rude man]

Ok, are the directions of the magnetic field around the rectangle wrong?

They're wrong.
Set up a coordinate system x to the right, y up, z out of page. Then evaluate the various unit vectors.
E.g. for the top left segment we get i x -k = ?
Learn the circular +/- i ↔ +/- j ↔ +/- k ↔ +/- i diagram for the signs. I find it a whole lot easier than twisting my hand and fingers into unnatural shapes ...