Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

I am trying to understand torque on a current loop which is placed in a uniform $\vec{B}$-field.

Image (http://i.stack.imgur.com/oNO8a.jpg)

It says that $\vec{F}_2$ and $\vec{F}_4$ have the same magnitude but different direction, which makes the net force zero, but I don't understand why the net torque becomes zero. F1 and F3 is perpendicular to the field which F2 and F4 isn't

It says the reason why it's zero is because the line of action is through the center of the loop.

How can this be a problem? Can't it just flip the other way as well????

And if torque = 0, is there then no rotation????

share|improve this question
1  
The image has the text "a torque acts to align the normal vector $\vec n$ with the direction of the field". Where does it say the torque is zero? Please refine your question. –  Alfred Centauri Jun 23 '13 at 22:12
    
The torque is zero only when $\theta=0$. –  leongz Jun 23 '13 at 22:19

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.