• Support PF! Buy your school textbooks, materials and every day products Here!

Finding electric potential difference to stop a electron between 2 plates

  • Thread starter mjolnir80
  • Start date
  • #1
53
0

Homework Statement



Question: an electron with a velocity of 5.0x10[tex]^{}6[/tex] m/s is injected into a parallel plate apparatus through a hole in the positive plate. it moves across the vacuum between the plates. what would the potential difference have to be in order to stop the electron 25% of the way across the gap?



Homework Equations


conservation of energy eqations and electromagnetic equations

The Attempt at a Solution


if we set the base line at the positive plate:
E[tex]_{}kinetic 1[/tex] + E[tex]_{}electric potential 1[/tex] = E [tex]_{}electric potential 2[/tex]

Vq + 1/2 mV[tex]^{}2[/tex] = Vq(0.75) <---- (to account for the 25%)

V(-1.6 x 10[tex]^{}-19[/tex] ) + 1/2 (9.1 x 10[tex]^{}-31[/tex] )(5x10[tex]^{}6[/tex]) [tex]^{}2[/tex] = V(-1.6x10[tex]^{}-19[/tex])(.75)

when i do this my answer does not come out to what it is supposed to (which is 285 j/c)
what am i doing wrong
 

Answers and Replies

  • #2
G01
Homework Helper
Gold Member
2,665
16
I get 285V when I work through your numbers. Your doing the problem correctly, but you may have made an error in computing the numbers. Check your calculations for an error.
 
  • #3
53
0
kewl thanks for confirming that
 

Related Threads for: Finding electric potential difference to stop a electron between 2 plates

Replies
19
Views
16K
Replies
4
Views
10K
Replies
8
Views
5K
Replies
1
Views
2K
  • Last Post
Replies
10
Views
6K
  • Last Post
Replies
5
Views
3K
Replies
1
Views
7K
Top