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How Fast is the Electron Moving (Check My Work)

  1. Oct 9, 2009 #1
    An electron is initially at rest in a vacuum in a region where the potential is 0V. It is attracted by, and accelerates toward, a positively-charged metal plate at a potential of +12,000V. Assuming no other forces act on the electron, how fast is it moving when it hits the metal plate? Mass of electron is 9.1*10^-31kg

    Delta PEe= qe(deltaV)...........qe= 1.6*10^-19
    KEi+PEi=KEf+PEf
    KEf= PEi-PEf= -delta PE.............because KEi is zero
    1/2*m*vf^2= -qe(deltaV)
    vf=[-2qe*deltaV/m]^1/2

    Calculated PEe= (-1.6*10^-19)(12000)= -1.92*10^-15
    Vf= [-2(-1.92*10^-15)/9.1*10^-31kg]^1/2= 6.50*10^7m/s
    Final Answer: 6.50*10^7m/s

    Is that correct? If not, where am I going wrong? Any help would be greatly appreciated.
     
  2. jcsd
  3. Oct 9, 2009 #2

    rl.bhat

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    Homework Helper

    It is correct.
     
  4. Oct 9, 2009 #3
    Great! Thanks.
     
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