Register to reply

Electric potential at point x on the axis of a ring of charge density eta

by Bng1290
Tags: axis, charge, density, electric, point, potential, ring
Share this thread:
Oct21-10, 09:55 AM
P: 5
1. The problem statement, all variables and given/known data
A circular disk of radius R and total charge Q has the charge distributed with surface charge density [tex]\eta[/tex] = cr, where c is a constant. Find an expression for the electric potential at distance z on the axis of the disk. Your expression should include R and Q, but not c.

2. Relevant equations

[tex]\eta[/tex]=cr where c is constant

3. The attempt at a solution
So what I did was to sum all Vi and i was able to pull (1/4pi[tex]\epsilon[/tex]) and (1/sqrt(z^2+R^2) out which leaves me with Q left in the sum which I know i need to relate to [tex]\eta[/tex] in some way. The problem I'm having here is that I just don't understand how to work with [tex]\eta[/tex]=cr in such a way as to get rid of the constant c in my answer.

I feel like I'm not grasping this problem as a whole so any help would be wonderful. Thanks!
Phys.Org News Partner Science news on
Flapping baby birds give clues to origin of flight
Prions can trigger 'stuck' wine fermentations, researchers find
Socially-assistive robots help kids with autism learn by providing personalized prompts
Oct22-10, 01:18 AM
P: 17
To eliminate c, since \eta = cr, you can integrate the charge density over the disk to compute the total charge, Q. This should give you c in terms of Q and R.
Oct22-10, 07:24 AM
P: 5
Nice! Thanks so much!

Register to reply

Related Discussions
Gravitational potential of a ring at an off axis point Advanced Physics Homework 10
In the Electric field of a Continuous Charge Distribution, what is conti.. exactly? Electrical Engineering 2
Anyone familiar with centrifugal potential and brachistochrone in polar coords? Advanced Physics Homework 7
A couple of electric potential theory problems Introductory Physics Homework 1
Does an electric charge curve spacetime ? Special & General Relativity 119