Motion of Charged Particles in Electric Fields

Click For Summary

Homework Help Overview

The problem involves the motion of an electron that is accelerated through a potential difference and subsequently enters deflecting plates. The objective is to calculate the deflection distance of the electron while considering its initial velocity and the forces acting on it due to the electric field.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • The original poster attempts to determine the initial velocity of the electron using energy equations and expresses confusion about the next steps, particularly regarding the need to separate horizontal and vertical components of motion.
  • Some participants suggest using concepts from projectile motion to analyze the problem, while others question the validity of specific equations in the context of constant acceleration.

Discussion Status

The discussion is ongoing, with participants exploring different methods to approach the problem. Some guidance has been provided regarding the application of projectile motion principles, but there is no explicit consensus on the best path forward.

Contextual Notes

Participants note the potential confusion arising from the need to apply different equations for constant velocity versus constant acceleration, as well as the relevance of kinematic equations in this context.

CARL0001

Homework Statement


This is the question: An electron at rest of mass 9.11 × 10−31 kg is accelerated through a potential difference of 350 V. It then enters some deflecting plates of 50 V with dimensions as shown. Calculate the distance x (deflection of the electron) (Charge on an electron is 1.6 × 10−19 C)

Given Diagram: https://gyazo.com/73ada230623b2ba00a80f5be8001fade

Homework Equations


W = Fd = ½mv2 = qΔV , Δt = Δd / v

https://gyazo.com/0b2211e627a646ec5437e72c0848e6d9

The Attempt at a Solution


So the question is asking to find the displacement in the y direction which is x on the diagram. i first found the original velocity between the vertical plates. in order to get the original velocity i used the following equation qΔV= ½mv2. i rearranged the formula and solved for v which i got to be 1.1 x 10^7 m/s. from my understanding this is the initial velocity of the electron when it enters the horizontal plates. I'm confused where to go from here. i can't find any practice examples similar to this type of question. I'm confused whether or not you need to split this section into vertical and horizontal components. i think next i have to find the electric force and then use that to find the acceleration. then i think you can use
Δt = Δd / v to find the time between the plates. after this i think you can find the displacement using one of the 5 kinematic equations. however I'm confused since i don't know if you need to split this up into different components.
 
Physics news on Phys.org
Have you covered projectile (parabolic motion) in uniform gravitational fields? If so you can use similar techniques to solve your problem.
HINT In one direction the electron continues moving with constant velocity and perpendicular to that it moves with constant acceleration.
 
Dadface said:
Have you covered projectile (parabolic motion) in uniform gravitational fields? If so you can use similar techniques to solve your problem.
HINT In one direction the electron continues moving with constant velocity and perpendicular to that it moves with constant acceleration.
No I'm not familiar with this method, however is my method correct?
 
CARL0001 said:
Δt = Δd / v
No, that is only valid for constant velocity. Here you have constant acceleration in the direction of the field. That makes it just like projectiles in near-Earth gravity.
Look up SUVAT.
 

Similar threads

  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 58 ·
2
Replies
58
Views
6K
  • · Replies 7 ·
Replies
7
Views
3K
Replies
4
Views
1K
Replies
9
Views
2K
Replies
14
Views
3K
  • · Replies 26 ·
Replies
26
Views
3K
Replies
4
Views
3K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 42 ·
2
Replies
42
Views
8K