Displacement of an electron between two plates

  • Thread starter oy_katet
  • Start date
  • #1
3
0

Homework Statement


In an oscilloscope, an electron is accelerated from rest through a voltage of 1.14x103 V. It then passes through deflecting plates 2.00 cm apart, across which there is a voltage of 412 V. Its velocity when it enters the plates is perpendicular to the electric field of the plates. When the electron leaves the plates, what distance will it have moved toward the positive plate? The length of the plates are 4.00 cm.

The answer is 7.23x10-3 m


Homework Equations



Givens:
vi= 0
Va= 1.14x103 V
Vd= 412 V
length of plate = 4 cm = 0.04 m
d= 2 cm= 0.02 m

Equations:
1/2mv2= Vaq
t=length of plate/v
E=Vd/d
F= Eq
a= F/m
x=1/2at2


The Attempt at a Solution



So, because it's an electron
q= 1.6x10-19
m= 9.11x10-31

Using the above equations and plugging in the givens, I've gotten:

v= 2.001x107 m/s

t=1.0x10-9 s

E= 20600 v/m

F= 3.296x10-15 N

a= 3.618x1015 m/s2

x= 1.809x10-3 m


which is not the right answer :( I'm not very good at physics so I'm having a hard time figuring out what I'm doing wrong.
 

Answers and Replies

  • #2
ehild
Homework Helper
15,543
1,914
Using the above equations and plugging in the givens, I've gotten:

v= 2.001x107 m/s
Correct...

t=1.0x10-9 s

here is a mistake: The electron travels along the length of the plate with the v=2.00 m/s so the time is 2.0x10-9 s

ehild
 
  • #3
3
0
Correct...



here is a mistake: The electron travels along the length of the plate with the v=2.00 m/s so the time is 2.0x10-9 s

ehild

Wellp, I'm just a big ol' dummy! I can't believe I made that oversight. Thanks so much!!!
 

Related Threads on Displacement of an electron between two plates

Replies
2
Views
5K
Replies
1
Views
2K
  • Last Post
Replies
1
Views
13K
Replies
2
Views
1K
  • Last Post
Replies
12
Views
6K
  • Last Post
Replies
6
Views
462
Replies
5
Views
834
Replies
1
Views
10K
Replies
15
Views
2K
Replies
3
Views
5K
Top