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!

Electron velocity

  1. Aug 30, 2010 #1
    1. The problem statement, all variables and given/known data

    Calculate the velocity of an electron with 3 eV energy. This electron is accelerated by a constant field of 10 V/cm (parallel to the electron velocity) for 0.1 cm. What is the new electron velocity?

    My other problem is the unit for the electric field . it bothers me: V/cm usually it is N/C
    2. Relevant equations

    Please can i have some suggestions?

    3. The attempt at a solution
    3eV=3 x 1.6E-19=4.8E-19 joules=1/2 mv^2, so v^2=4.8E-19/4.5E-31=1E12
    so v=10^6 metres/sec.
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Aug 30, 2010 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    You should be aware of the fact that 1 V/m = 1 N/C. So 1 V/cm is how many N/C?
  4. Aug 30, 2010 #3
    100 N/C
    thank i forgot all those units!

    to find the final speed, i use the formula (Vfinal)^2-(Vinitial)^2=2a*(0.1 e-2)
    when i did I found Vfinal =1.03 e6 m/s

    the velocity difference i think is very small , it seems not right. did i do the question corretly?
    thank you
    Last edited: Aug 30, 2010
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook