# Homework Help: Continuous Surface Sources

1. Jan 28, 2012

### technicolour1

1. The problem statement, all variables and given/known data
Find the total charge on a circular disc of radius ρ = a if the charge density is given by
ρs = ρs0 (e^−ρ) sin2 φ C/m2 where ρs0 is a constant.
Are the two limits of integration from 0 -> a for ρ and 0->2∏ for φ? In the example given in the notes, ρ varies, instead of being a constant value. Does this mean that I cannot integrate ρ in this problem?

2. Relevant equations

Q = ∫ρdS

3. The attempt at a solution

Q = ∫∫ρs0 (e^−ρ) sin^2 (φ) dφdρ...

Last edited: Jan 28, 2012
2. Jan 28, 2012

### Spinnor

With the sin term it looks like there is as much positive as negative?

Edit, now I see the sin^2