Force on wire

  • Thread starter Fisicks
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  • #1
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Homework Statement


A stiff wire 50cm long is bent at a right angle in the middle. One section lies along the z axis and the other is along the line y=2x in the xy plane. A current of 20A flows in the wire down the z axis and out the line in the xy plane. The wire passes through a uniform magnetic field give by B=.318i. Determine the magnitude and direction of the total force on the wire.



Homework Equations


F=BILsin(theta)



The Attempt at a Solution


For the z axis part of the wire, I get F=(20)(.25)(.318)
For the xy plane part of the wire I get (20)(.25)(.318)(.447)
Now when i square these forces take the sum and square root the answer, I don't get the magnitude I should. This problem is pretty straight forward, not quite sure why I cant get it.

Thanks guys
 

Answers and Replies

  • #2
SammyS
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0.447 ≈ cos(θ), where θ is the angle the xy-plane portion of the wire makes with the x-axis (also the direction of the B field.

sin(θ) = 2/√(5) .
 

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