Magnetic force problem

  • Thread starter terryds
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  • #1
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Homework Statement



35k4ww3.png


As shown in figure above, a conductor RS with 2 m length which is powered with currents is put in a 0.5 T magnetic field. If the force generated by the conductor is 1 N into-the-screen, then the magnitude and direction of the current in conductor is ...

A. 1 A from R to S
B. 1 A from S to R
C. 2 A from R to S
D. 2 A from S to R
E. 5 A from R to S

Homework Equations



F = BIL sin θ

The Attempt at a Solution



1 = 0.5 I 2 sin 90°
I = 1 Ampere

And, the direction is from S to R
(I point my 4 fingers to the right side, my palm inward, so the thumb (current) points upward)

Is it correct?? I need to make sure about this... I'm self-studying :smile:
Thanks in advance
 

Answers and Replies

  • #2
BvU
Science Advisor
Homework Helper
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Hi,

PF isn't really good at stamp-approving exercises -- it doesn't really help you if we do and you're found wrong anyway.
(It also antagonizes teachers in general :smile:).
You actually need to convince yourself that what you did is correct (because you fully understand what you did, checked it, etc.).

On the other hand, if I do the exercise I get the same result. I can't remember al these rules, but I can remember the Lorentz force $$\vec F_L = q\left (\vec E+\vec v\times\vec B\right )$$. And if I imagine a corkscrew and rotate ##\vec v## over the smallest angle to ##\vec B## I see that it goes into the page if ##\vec v## points from S to R

--
 
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  • #3
392
13
Hi,

PF isn't really good at stamp-approving exercises -- it doesn't really help you if we do and you're found wrong anyway.
(It also antagonizes teachers in general :smile:).
You actually need to convince yourself that what you did is correct (because you fully understand what you did, checked it, etc.).

On the other hand, if I do the exercise I get the same result. I can't remember al these rules, but I can remember the Lorentz force $$\vec F_L = q\left (\vec E+\vec v\times\vec B\right )$$. And if I imagine a corkscrew and rotate ##\vec v## over the smallest angle to ##\vec B## I see that it goes into the page if ##\vec v## points from S to R

--
Alright, thanks..
Sometimes it's just hard to fully confident that it's 100% correct if I'm self-studying..
Thank you for your response anyway :smile:
 
  • #4
BvU
Science Advisor
Homework Helper
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I believe you. Hats off & good luck !
 
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