Accelerating electrons

  • Thread starter Gyroscope
  • Start date
  • #1
Gyroscope

Homework Statement


An electron is accelerated from rest through a potential difference of V volts. What is the final velocity?

I did:
[tex]qV=\frac{mc^2}{\sqrt{1-\frac{v_f^2}{c^2}}}[/tex]

And solve for v, but I get an unreal answer. What am I doing wrong?!

Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
hage567
Homework Helper
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Why are you using relativistic energy?
 
  • #3
Gyroscope
Because there is an high potential difference. If I use non-relativistic energy it gives a speed higher than the speed of light. :rolleyes:
 
  • #4
hage567
Homework Helper
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Could you post more of the question and your work?
 
  • #5
236
0
If I'm not mistaken(Memory sometimes betray me) qV=(Gamma-1)mc^2
 
  • #6
Gyroscope
ziiad this is the relativistic kinetic energy, what I need is the relativistic change in kinetic energy.
 
  • #7
Gyroscope
No, you are right. What a stupid mistake of mine. :( Thanks, mate.
 
  • #8
236
0
Don't worry, we all make mistakes, they key part was "...accelerated from rest..."
 

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