1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Cant uderstand some parts this another problem

  1. Aug 28, 2009 #1
    here is the problem and solution:
    http://i30.tinypic.com/2w2mnap.jpg

    why they divide into two cases?

    then they find a magnetic field

    but we dont have any electricity flowing??

    the i recognized the formula for a magnetic field from a wire
    but when we find a the formula from the biotsavart law
    the oly direction is dlX[tex]\hat{r}[/tex]

    there is no [tex]\vec{\theta}[/tex] there
    because thus in Cartesian coordinates the direction always changes

    how they get this theta direction thing??
     
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted