Solved

Simple Coulombs Law Problem

Posted on 2008-10-05
2
373 Views
Last Modified: 2012-06-22
A 2 x 10^(-6) C charge is located at A(4,3,5) in free space, find E_rho, E_phi, E_z, at O(8,12,2). (The problem wants the electric field components in cylindrical components).

Since the points are given in Cartesian, I solved the problem in Cartesian coordinates.

 E = [2x10^(-6)] / [4 * pi * 8.854 x 10^12 * sqrt[106]^3] [ 4a_x + 9a_y + 3a_z]

I get:

 E = 65.88a_x + 148.24a_y - 49.41a_z

Since in cylindrical components the z component is the same as the z component in Cartesian, I was able to verify that at least the z component is correct. However, I try to determine E_rho and E_phi and cant seem to get the right answer, which is (159.7 and 27.4 respectively).

I do E_rho = 65.88 cos( arctan( 148.24 / 65.88) ) + 148.24 sin( arctan( 148.24 / 65.88) )

and E_phi = -65.88 sin ( arctan( 148.24 / 65.88) ) + 148.24 cos( arctan( 148.24 / 65.88) )

What am I doing wrong?
0
Comment
Question by:BrianGEFF719
  • 2
2 Comments
 
LVL 27

Accepted Solution

by:
aburr earned 500 total points
ID: 22651427
Try
E_rho = magnitude of E in the r direction as (x^2 + y^2) where x and y are the magnitudes of E in the x and y directions of Cartesian cords.
E_ phi = magnitude of E in the phi direction as arctan y/x where x and y are the magnitudes of E in the x and y directions of Cartesian cords.
I think you may be confusing a bit of spherical coords in here.
0
 
LVL 27

Expert Comment

by:aburr
ID: 22651459
That is
E_rho = sqrt(x^2+y^2)
0

Featured Post

Networking for the Cloud Era

Join Microsoft and Riverbed for a discussion and demonstration of enhancements to SteelConnect:
-One-click orchestration and cloud connectivity in Azure environments
-Tight integration of SD-WAN and WAN optimization capabilities
-Scalability and resiliency equal to a data center

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Simple formula for calculating R-Squared between 2 stocks 8 61
Math homework question 5 98
Math question 3 97
deducing meaning of a word from its prefix-question 7 74
Complex Numbers are funny things.  Many people have a basic understanding of them, some a more advanced.  The confusion usually arises when that pesky i (or j for Electrical Engineers) appears and understanding the meaning of a square root of a nega…
When we purchase storage, we typically are advertised storage of 500GB, 1TB, 2TB and so on. However, when you actually install it into your computer, your 500GB HDD will actually show up as 465GB. Why? It has to do with the way people and computers…
This is a video describing the growing solar energy use in Utah. This is a topic that greatly interests me and so I decided to produce a video about it.
I've attached the XLSM Excel spreadsheet I used in the video and also text files containing the macros used below. https://filedb.experts-exchange.com/incoming/2017/03_w12/1151775/Permutations.txt https://filedb.experts-exchange.com/incoming/201…

839 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question