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!

Electron microscope particle relativistic mass

  1. Oct 4, 2015 #1
    1. The problem statement, all variables and given/known data
    They were going to purchase an electron microscope, and wanted the electrons velocity to be as high as 25% of the speed of light after acceleration. There was a microscope at hand that had an accelerating voltage of 40 kV.
    a) How large is the electrons relativistic mass when it hits the target expressed in m0?
    b) Is the voltage high enough to reach at least25% of the speed of light?


    2. Relevant equations
    qV=K
    mv2/2=K
    E2=m2c2+p2c2
    E=K+mc2
    p=mvγ


    3. The attempt at a solution
    Don't know where you use the rest mass and where you get the relativistic mass? Not sure how to figure this out.
     
  2. jcsd
  3. Oct 4, 2015 #2

    ehild

    User Avatar
    Homework Helper
    Gold Member

    The equation in red is wrong. The relativistic kinetic energy is not 1/2 mv2. In the other formulae, m means the invariant mass (called also rest mass). The relativistic mass is γm. http://www.britannica.com/science/relativistic-mass
     
  4. Oct 4, 2015 #3
    γ=qV/m0c2+1 ?
     
  5. Oct 4, 2015 #4

    ehild

    User Avatar
    Homework Helper
    Gold Member

    Yes, but you need to give the relativistic mass.
     
  6. Oct 4, 2015 #5
    I was thinking γm0=mrel?

    So (qV/m0c2+1)m0=mrel?

    From where do I get the v to answer b?
     
  7. Oct 4, 2015 #6

    ehild

    User Avatar
    Homework Helper
    Gold Member

    There is an error also in the equation in red.
    It should be E2=(mc2)2+p2c2
    Determine p, and you get v from 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: Electron microscope particle relativistic mass
  1. Relativistic Electron (Replies: 2)

  2. Relativistic particles (Replies: 10)

  3. Relativistic particles (Replies: 7)

Loading...