1. Not finding help here? Sign up for a free 30min 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!

Electric Field with three negative point charges in a line

  1. May 29, 2014 #1
    1. The problem statement, all variables and given/known data
    Find the magnitude of the electric field this comination of charges produces at point P, which lies 6.00cm from the -2.00μC charge measured perpendicular to the line connecting the three charges.


    2. Relevant equations
    E=k[itex]\frac{Q}{r^{2}}[/itex]
    F=k[itex]\frac{q_{1}q_{2}}{r^{2}}[/itex]
    F=[itex]\frac{E}{q}[/itex]
    k[itex]\approx9*10^{9}[/itex]
    3. The attempt at a solution
    Conversions to the correct units were done prior to plugging values into eqn.

    To my understanding the net electric field is the sum of all electric fields from each point charge.
    So I found E[itex]_{-5μC}[/itex]=-4,500,000 and the same goes for the other -5μC point charge; E[itex]_{-5μC}[/itex]=-4,500,000 , and for the -2μC point charge I got E[itex]_{-2.00μC}[/itex]= -5,000,000

    For E[itex]_{-5μC}[/itex] I calculated and then plugged in [itex]\sqrt{(8cm^{2}+6cm^{2}}[/itex]≈0.1m


    Results summed up to E[itex]_{-5μC}[/itex]+E[itex]_{-5μC}[/itex]+E[itex]_{-2.00μC}[/itex]=(-4.5*10[itex]^{6}[/itex])+(-4.5*10[itex]^{6}[/itex])+(-5.0*10[itex]^{6}[/itex])= -1.40*10[itex]^{7}[/itex]

    The question only asked for magnitude so I'm assuming direction doesn't really matter at this point. What am I doing wrong? Please help.
     
  2. jcsd
  3. May 29, 2014 #2

    tms

    User Avatar

    So far so good.

    The electric field is a vector, and you must take the vector sum of the fields of the three charges.
     
  4. Jun 10, 2014 #3
    Thank you!!


    Forgot to log in after having solved it.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Electric Field with three negative point charges in a line
Loading...