# Homework Help: Need help with electric field question

1. Nov 11, 2009

### sijanranabhat

i have a test, and i cant find a answer to this question .
" Draw the general shape of the electric field in the region surrounding a long thin rod of length L with a positive charge on it. At a point P above and to the side of the rod, describe in detail without math, how to determine the magnitude and direction of the field at that point."

2. Nov 12, 2009

### ApexOfDE

I think, to solve this problem, you will need to imagine that there is a test positive charge at point P. Based on Couloumb force, you know that direction of C. force at P is away from the rod. You also know that directions of force and e. field is parallel (in case of positive charge) ==> ...

About how to determining a magnitude of e. field without math, you may draw e.field vectors from several points in the rod to point P. Each point will create e.field with magnitude dE at P. Using vectors to find value of dE in each axis ==> ...

p/s: i am not sure about how to determine magnitude of e.field without math. It is too hard to explain :(

Hope this help.