# [Help] in the integration of electric field

1. Mar 22, 2014

### bibo_dvd

Hello guys !! :)

i need your help in the integration which is used to calculate the total charge in the electric field

in a continuous volume charge distribution

in this example i can't understand how the integration was done ..so please help me with this :)

The example :

iam not very good in integration so i need your help ...Thanks guys !!

2. Mar 22, 2014

### SteamKing

Staff Emeritus
What, specifically, are you having trouble with? If you are not very good at integration, then you need to review the subject and work some practice problems.

3. Mar 22, 2014

### bibo_dvd

the problem is that iam not very good at integration :( and i don't know from where should i start ..i mean which book or tutorial should i start with to help me with this type of examples ?? :)

4. Mar 22, 2014

### jim hardy

Looks to me like there's a mistake in the textbook
Blue figure gives charge as so many microcoulombs per cubic meter

and text below gives it as same number of microcoulombs per square meter.

So it's just a triple integration to get volume, but you integrate wrt z last because ρ is a f(z).

I'd solve it for volume first with ρ a constant(1?), to gain confidence in my ability to triple integrate.
Then go back and include the p(z) in the third intergral.

At least I think that's what i would do ... It's been decades.

Might be you need to go back to your calculus book. It is important to work so many problems they become second nature.

old jim

old jim