Electric Flux/Gauss' Law

[robbondo]

1. The problem statement, all variables and given/known data

A point charge q_{1} = 4.15 \times 10^-6 is located on the x-axis at x = 1.80 m, and a second point charge q_{2} = -5.80 \times 10^-6 C is on the y-axis at y = 1.10 m. What is the total electric flux due to these two point charges through a spherical surface centered at the origin and with radius r = 1.45 m?
Take the permittivity of free space to be 8.85 \times 10^{-12}\:{\rm C}^{2}/{\rm N \cdot m}^{2}.


2. Relevant equations

\phi_{E} = \frac{Q_{enclosed}}{\epsilon_{0}}




3. The attempt at a solution

I just divided the one charge inside the sphere by epsilon naught.

\frac{q_{2}}{\epsilon_{0}}

So I get, -6.55 \times 10^{5}

I'm sure I screwed something obvious up, any suggestions?

[dynamicsolo]

2. Relevant equations

\phi_{E} = \frac{Q_{enclosed}}{\epsilon_{0}}
3. The attempt at a solution

I just divided the one charge inside the sphere by epsilon naught.

\frac{q_{2}}{\epsilon_{0}}

So I get, -6.55 \times 10^{5}

I'm sure I screwed something obvious up, any suggestions?

Why are you sure you messed up? Show the calculation you made and also be sure to show your units.

[robbondo]

I know I'm wrong because this hw's online and I got it wrong, and I loose points for every wrong answer suckily. Well the units for q were nanocoulombs which I changed to coulombs and then epsilon naught is {\rm C}^{2}/{\rm N \cdot {m}}^{2} . So they cancel out do give {\rm N \cdot m}^{2}/ \rm C}

Calculation was \frac{-5.8 \cdot 10^{-12}}{8.85 \cdot 10^{-12}}

crap... I used the wrong changing of units it 1 \cdot 10^{-9} coulombs per nanocoulombs... not -6.

Thanks solo.

[dynamicsolo]

crap... I used the wrong changing of units it 1 \cdot 10^{-9} coulombs per nanocoulombs... not -6.

Thanks solo.

Well, that was easy on me... As a suggestion, when you present a problem in the forum, type it in exactly as it appeared originally. That would have made the SI prefix error easy to spot. Your method was correct!