Finding the electric field between two parallel plates

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Homework Help Overview

The problem involves finding the electric field between two parallel plates, with given parameters for an electron's initial velocity, charge, and mass. The original poster expresses difficulty in solving the problem due to missing information about the geometry of the plates.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the necessity of additional information regarding the length and distance between the plates to solve the problem. There are attempts to relate kinematic equations to the electric field but uncertainty remains about the completeness of the provided data.

Discussion Status

There is a consensus among participants that the problem lacks sufficient information for a complete solution. Some suggest the possibility of reaching out to the professor regarding the unclear aspects of the assignment, while others reflect on past experiences with the professor's handling of similar situations.

Contextual Notes

Participants note that the homework must be submitted in class on paper, and there is a mention of the professor's history of extending deadlines when mistakes are identified in assignments.

LuigiAM
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Homework Statement



Hi everyone! This is the homework problem I'm struggling with!

CEUQSBT.jpg


Initial velocity = 107 meters per second
The particle is an electron, so:
Charge = -1.6 x 10-19 coulombs
Mass = 9.11 x 10-31 kilograms

Homework Equations



Kinematic formula x = vot + 1/2 at2
Newton's law: Force = mass times acceleration
Magnitude of electric field = force over charge

The Attempt at a Solution



I'm really at wit's end with this one guys :(

Basically, I've been trying to use kinematics from mechanics to solve this problem, but the way I've been doing it I haven't been able to get to the solution without knowing the length of the plates and the distance between them.

As you can see the professor gives us the answer to help guide us through the solution, but I just can't see how to get to it for this one problem.

My homework is for thursday so I have a lot more time to try and think of a solution, but I thought maybe you guys could maybe give me a tip about what step I may be missing.

This is the work I've done so far. I've assigned variables to represent the length of the plates and the distance between them. The only solution I was able to get was in terms of those variables. I assume there's a way to make them cancel out with something? Thanks for any help!

My work so far:

nh5EqAt.jpg
 

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I think you're right that you need more information about the plate geometry.
 
Clearly there is not enough information. If you make the horizontal distance greater, all the given data can stay the same but the field required would be less.
 
Seriously? :frown:

Oh boy. I suspected that at first but I was sure that I was missing something. Should I write to the professor? He's over 80 years old so I don't want to offend him.
 
LuigiAM said:
Seriously? :frown:

Oh boy. I suspected that at first but I was sure that I was missing something. Should I write to the professor? He's over 80 years old so I don't want to offend him.
Is it the prof's diagram? Quite sure there's no other data with it?
You could submit the answer you have... or do you have to submit it to a bot?
 
LuigiAM said:

Homework Statement


Basically, I've been trying to use kinematics from mechanics to solve this problem, but the way I've been doing it I haven't been able to get to the solution without knowing the length of the plates and the distance between them.
Don't feel bad, I agree you need both h and d to obtain E.
So now someone else can prove us both wrong ... :smile:
 
haruspex said:
Is it the prof's diagram? Quite sure there's no other data with it?
You could submit the answer you have... or do you have to submit it to a bot?

Yeah it's his diagram. There's nothing else, I just took a screenshot of the third question. We have to give it in class on paper

Last semester in mechanics he sometimes sent us emails to extend the date of a homework when he realized he had mistakes in them. I assume he might do the same again :sorry:
 

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