# Gauss's law, cylinder

Discussion in 'Homework Help' started by ihatereg, Feb 13, 2010.

1. ### ihatereg Thread Starter New Member

Mar 10, 2009
9
0
http://img404.imageshack.us/img404/4148/gauss3j.png (infinitly long)

$\Phi=\Phi_{0}(1-{r \over R}) {C \over m^2}$

What's the charge of the cylinder of length L?

I have done some calculations, but they were all wrong (checked by teacher).

2. ### nubelube New Member

Jan 3, 2010
16
1
1. What problem are you try to solve (and what are your assumptions? e.g. charge density)? What do your symbols denote (e.g. what are C and m)?
2. What did you do in your attempt to solve it? (and why, if it's not obvious)

3. ### lmartinez Active Member

Mar 8, 2009
224
6
Are you attempting to find the electric field at a given distance due to a uniform line charge of an infinite length whose charge per unit length is given? ...

4. ### ihatereg Thread Starter New Member

Mar 10, 2009
9
0
C over m are units. It should be m^3 actually.

Anyway, question I gave you is additional one. The more important one is what is the electric field when r<R?

5. ### ihatereg Thread Starter New Member

Mar 10, 2009
9
0
C over m are units. It should be m^3 actually.

Anyway, question I gave you is additional one. The more important one is what is the electric field when r<R?

6. ### mik3 Senior Member

Feb 4, 2008
4,846
69
When r is less than R the electric field is zero.

Mar 10, 2009
9
0
8. ### mik3 Senior Member

Feb 4, 2008
4,846
69
You can assume an area inside the cylinder and calculate the net electric flux throught it.

Mar 8, 2009
224
6