# How do i find the higher electric field of these two

1. Mar 29, 2009

### Dell

given a ball and an infinite pipe, both with the same radius and same charge density $$\sigma$$
what is the total electric field at the meeting point of the 2 if we bring them close together so that they touch at point A?

what i did was:

the ball has spherical symetry and the pipe has cylindrical symetry, so those are the shapes i will use for my gauss law,

since RA=R

for the ball
$$\Phi$$=EA=E(4$$\Pi$$R2)=$$\sigma$$(4$$\Pi$$R2)/$$\epsilon$$0

E=$$\sigma$$/$$\epsilon$$0

for the pipe
$$\Phi$$=EA=E(2$$\Pi$$R*L)=$$\sigma$$2$$\Pi$$R*L)/$$\epsilon$$0

E=$$\sigma$$/$$\epsilon$$0

does this mean that the total field at point A will be 0 since they have the same field in opposite directions?
does that make sense?

2. Mar 29, 2009

### Redbelly98

Staff Emeritus
Looks right to me.