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: Electric potential question

  1. Sep 15, 2005 #1
    I have solved these and got an answer but i have no idea if i have the right work or answer. Can any one help me with any of these questions? or just tell me what the answer is so i know if i have done it right. Thanx.

    1. A particle (charge 7.5x10^(-6)C)is released from rest at a point on the x-axis, x=0.1m. It begins to move due to the presence of a 2.0x10^(-6)C charge which remains fixed at the origin. What is the kinetic energy of the particle at the instant it passes the point x=1.0m?

    2. A charge of uniform density (0.80 nC/m) is distributed along the x-axis from the origin to the point x=0.1m. What is the electric potential (relative to zero at infinity) at a point x=0.18m, on the a-axis?
     
  2. jcsd
  3. Sep 15, 2005 #2

    quasar987

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    What have you done?
     
  4. Sep 15, 2005 #3
    Here's what i did

    1. let *=change in
    *K=-*U
    *K+*U=0
    *U=q(*V)
    *V=V2-V1=(k(q1)/r1)-(k(q2)/r2)=(k(7.5nC))/.9-(k (2nC))/.1=1.05x10^5
    q(*V)=-7.875x10^-1
    *K=7.875x10^-1
    --------------------------------------------------------------

    2. V=k(.8nC)/.1=72, i'm pretty sure this one is wrong though.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook