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!

Help With Magnitude-Angle Notation

  1. Jan 26, 2010 #1
    1. The problem statement, all variables and given/known data
    The figure below shows an uneven arrangement of electrons (e) and protons (p) on a circular arc of radius r = 2.24 cm, with angles θ1 = 31.0°, θ2 = 40.0°, θ3 = 41.0°, and θ4 = 27.0°. (a) What is the magnitude of the net electric field produced at the center of the arc? (b) What is the angle between the positive direction of the x axis and the electric field vector?

    http://edugen.wiley.com/edugen/courses/crs1650/art/qb/qu/c22/pict_22_14.gif

    2. Relevant equations
    [tex]E=\frac{kq}{r^2}=8.99 \times 10^9\ast\frac{1.602 \times 10^{-19}C}{(2.24 \times 10^{-2}m)^2}=2.86671 \times 10^{-6} N/C[/tex]


    3. The attempt at a solution
    I've solved for the magnitude simply by adding together for [tex]E_{net}[/tex], however I'm running into a problem with finding the angle of the electric field vector. I would think to start from the x-axis and go counterclockwise so that the first particle has an angle measure of 0°, then 31°, 71°, 112°, and lastly 153° for the final particle (most left). But adding these up in my Ti-89 (using M-A notation) gives me a wrong answer.

    I also various other combinations such as (starting from most left particle and not including the one on the x-axis): -27°, 112° -109° and -149°. Or -27°, -68°, 71°, 31°. Along with a few others.

    So I'm getting the right magnitude measurement, but not angle.
    Any help would be appreciated.
     
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

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