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Homework Help: Velocity of charges

  1. Apr 23, 2007 #1
    A proton of mass m and charge e is acclerated from rest through a potential difference V. The final speed of the proton is: ?

    I tried to figure this out.. but I can't find the equation for this.

    thank you
  2. jcsd
  3. Apr 23, 2007 #2


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    Homework Helper

    A common definition for electric potential (voltage) is the work done per unit charge (or Joules per Coulomb) to move a charge from infinity to a point in an electric field.

    With that knowledge, how much energy was transferred to this proton of charge e?

    Knowing that the proton of mass m was initially at rest, and has now gained some kinetic energy E, what is it's speed?
  4. Apr 23, 2007 #3
    so then answer is 2Ve/m...?
  5. Apr 23, 2007 #4
    i get 2q/m... how does voltage apply to the answer?
  6. Apr 23, 2007 #5


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    Staff Emeritus
    Science Advisor

    A charge of q accelerated across a potential V will have a change in energy of delta(E) = qV. If at rest, the change in energy is equal to the change in kinetic energy, assuming it is non-relativistic, which is a reasonable assumption in the case.
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