Go Back   Physics Help Forum > High School and Pre-University Physics Help > Electricity and Magnetism

Electricity and Magnetism Electricity and Magnetism Physics Help Forum

Reply
 
LinkBack Thread Tools Display Modes
Old Jan 13th 2010, 05:54 PM   #1
Junior Member
 
Join Date: Dec 2009
Posts: 26
Smile Parallel Plates Electric Field

Hello, I wonder if anyone could check my answer to this problem.

Thanks in advance

An electron is liberated from the lower of two parallel plates separated by a distance of 5mm. The upper plate has a p.d. of 1000v relative to the lower plate. How long does it it take for the electron to reach to upper plate.



I said F=ma=QE therefore QE=ma

and since E=V/d=1000/0.005=2x105

a=QE/m
a=3.513x1016m/s2!

Then using s=ut+1/2at2, t=5.335x10-10s.

Thanks again for any help

Mike
mikewhant is offline   Reply With Quote
Old Jan 14th 2010, 06:33 AM   #2
Senior Member
 
Join Date: Dec 2009
Posts: 209
Smile Look's fine to me

Originally Posted by mikewhant View Post
Hello, I wonder if anyone could check my answer to this problem.

Thanks in advance

An electron is liberated from the lower of two parallel plates separated by a distance of 5mm. The upper plate has a p.d. of 1000v relative to the lower plate. How long does it it take for the electron to reach to upper plate.



I said F=ma=QE therefore QE=ma

and since E=V/d=1000/0.005=2x105

a=QE/m
a=3.513x1016m/s2!

Then using s=ut+1/2at2, t=5.335x10-10s.

Thanks again for any help

Mike
Hi there,
As long as your initial velocity, u, was zero, the mass you used was that of an electron, and lastly the charge , Q, was that of an electron, then your answer is correct. 1000V applied to such a tiny mass should cause it to undergo a great acceleration. Again this assumes that gravity has no effect on the electron, which is typically considered true. Then you should be able to set 0.005 = (1/2)at^2, plug in the value of, a, that you got, and then solve for the time, t.
Many Smiles,
Craig

Last edited by clombard1973; Jan 14th 2010 at 06:36 AM.
clombard1973 is offline   Reply With Quote
Old Jan 14th 2010, 07:47 AM   #3
Senior Member
 
Join Date: Dec 2009
Posts: 209
Smile Yup you're correct

Hi there,
I just went through and solved the problem myself, I got both the same acceleration upon the electron that you did and the same time to traverse the distance from one plate to the other.

I feel pretty certain about my answer and since you have the same as I have, I'd feel pretty certain that you too also have the correct answer.

Nicely done!

Many Smiles,
Craig
clombard1973 is offline   Reply With Quote
Old Jan 14th 2010, 09:06 AM   #4
Junior Member
 
Join Date: Dec 2009
Posts: 26
Thumbs up

Thanks Craig, as always most helpful!

Take care,

Mike
mikewhant is offline   Reply With Quote
Reply

  Physics Help Forum > High School and Pre-University Physics Help > Electricity and Magnetism

Tags
electric, field, parallel, plates



Thread Tools
Display Modes


Similar Physics Forum Discussions
Thread Thread Starter Forum Replies Last Post
Electric field in a parallel plate capacitor Skyrim Electricity and Magnetism 1 Apr 28th 2011 03:50 PM
Electric Field between two infinitely long parallel planes dspaulding09 Electricity and Magnetism 0 Mar 1st 2010 04:56 PM
Parallel Plate Electric Field mikewhant Electricity and Magnetism 13 Jan 25th 2010 11:33 AM
Electric Fields and Parallel Plates mikewhant Electricity and Magnetism 11 Jan 13th 2010 06:14 PM
electric field between two plates tag16 Electricity and Magnetism 3 Sep 24th 2009 06:11 PM


Facebook Twitter Google+ RSS Feed