# magnitude and the direction of current Iw #13

in the figure , a rectangular current loop is carrying current I1=7 in the direction is located neal a long wire carrying a current Iw. The long wire is parallel to the sides of the rectangle. the rectangle loop hans length 0.80 and its sides are 0.70 and 0.10 from the wire. if the net force of the loop is to have magnitude of 4.6 and is to be directed towards the wire what must be the magnitude and the direction (from top to bottom or bottom - up in the sketch) of current Iw in the wire ?
______
|       |         |
|       |         |  0.80
|       |         |
|0.10 |_____|
|
|  >>0.70>>>
|
|
|any ideas ??
###### Who is Participating?

x

Commented:
What is the direction of the force on the loop if the direction of the current on the lonf wire is it from botton - up or top bottom?
0

Commented:
Do you know how to find the net force for a given current?
0

Author Commented:

a) ..well we know that B=m0*F/2pi*R
and F=I*dLB
b).. The F on the top and bottom will be zero

c) do i have to subtract the forces on the sides ?

0

Commented:
0

Author Commented:
i have seen the link before...
not quite sure if i have to subtract the forces though on the sides....i think i might have two die to the right hand rule the two forces have opposite directions because the I flows in opposite directions thus they repel each other..
0

Commented:
The force that the left side of the loop exerts on the right side of the loop is equal and opposite to the force that the right side of the loop exerts on the left side of the loop, so they add to 0 and you can can ignore them.
The only thing remaining that maters is the force that the long wire exerts on the left side of the loop and the force that the long wire exerts on the right side of the loop.
0

Author Commented:
so i will come up with F1 and F2 which stand for the force that the long wire exerts on the left side of the loop and the force that the long wire exerts on the right side of the loop.
Now the direction of the current on the lonf wire is it from botton - up or top bottom?
thanks again
0

Author Commented:
it the current is bottom up , then the force is towards the right of the sketch (the force vector points from left to right)
if the current is top-bottom the the force vector should point from right to left
0
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