# Magnetic force problem

1. May 12, 2016

### terryds

1. The problem statement, all variables and given/known data

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

2. Relevant equations

F = BIL sin θ

3. 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)

2. May 12, 2016

### BvU

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 ).
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

--

3. May 12, 2016

### terryds

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

4. May 12, 2016

### BvU

I believe you. Hats off & good luck !