Electron between charged plates

In summary, an electron enters the area between two charged plates and barely misses the top plate. The electron's kinetic energy and potential energy both increased by 0.12E6.
  • #1
Melawrghk
145
0

Homework Statement


An electron enters the area between two charged plates having a horizontal speed of 1.9E6. The space between plates is 1cm and the electron enters half way down from the top plate. The length of the plates is 2cm. Find the speed of the electron as it exists the space between plates barely missing the top plate.

The Attempt at a Solution


I figured it would be just an energy question, so I found the initial kinetic energy and the potential energy it would gain through the climb.

As a result though, the speed still stayed the same. I'm not sure if I'm thinking correctly?... Thanks in advance.
 
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  • #2
Seems to me that that when the electron leaves the plates is has a component of velocity in the x- direction and an acquired component of velocity in the y-direction. the magnitude of it's velocity is now larger than when it entered.This problem has a close similarity to a projectile motion problem. If I were solving it, I'd use that analogy.
 
  • #3
Thanks! I used two basic dynamics formulas for acceleration and distance and I got it! :)

It increased to 2.12E6, apparently.
 
  • #4
Can you explain which equations you used and how?
I have the same problem.
Thanks in advance.:)
 
  • #5
Yeah, for sure. Well you know that the electron enters 0.5cm from the top (halfway between the plates) and exists at the top's level. So it had to vertically travel 0.5cm. Since originally it only had an x-component (and this speed remains the same), it had to have some force acting on it 'causing acceleration.

First, I set out to find the time it took for the "journey". I took the length of the plate (2cm, in my case) and divided it by the horizontal speed. This yielded some time, let's call it "t".

Now, from mechanics, there is a formula:
d=(1/2)*a*t^2 and I used that to find the vertical acceleration (0.5cm, t=t).

Next you really have a few ways of doing this. The simplest is:
a=(delta)v/(delta)t = (vf-vi)/t
In that equatoin you know a and t, and you know that vi=0 (initial vertical speed). This equation will give you the vertical speed as the electron exists the space between plates.

Now use Pythagorean Theorem to find the net speed/velocity.

Hope this helped :)
 
  • #6
Thank you so much! This helped me a lot!
You are excellent at explaining what you did!

Thanks again :)
 

Related to Electron between charged plates

1. What is an electron between charged plates?

An electron between charged plates refers to a scenario where an electron is placed between two parallel plates with opposite charges. This creates an electric field that can affect the motion of the electron.

2. How does the electric field affect the motion of the electron?

The electric field exerts a force on the electron, causing it to accelerate towards the positively charged plate. The strength of the electric field and the charge of the plates determine the magnitude of the force.

3. What happens to the electron when it reaches one of the charged plates?

When the electron reaches one of the charged plates, it will experience a force in the opposite direction and start to decelerate. Depending on the strength of the electric field, the electron may oscillate back and forth between the two plates or eventually come to rest on one of the plates.

4. What is the significance of studying an electron between charged plates?

Studying an electron between charged plates allows scientists to better understand the behavior of charged particles in electric fields. This knowledge is crucial in many fields, such as electronics, particle physics, and electrostatics.

5. Can the distance between the charged plates affect the motion of the electron?

Yes, the distance between the charged plates can affect the motion of the electron. The strength of the electric field is inversely proportional to the distance between the plates, so a smaller distance will result in a stronger electric field and a greater force on the electron. This can impact the speed and trajectory of the electron between the plates.

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