A point charge q1=4.30 nC is located on the x-axis at x=2.30m, and a second point charge q2=-6.00 nC is on the y-axis at y=1.15m.
(a) What is the total electric flux due to these two point charges through a spherical surface centered at the origin and with radius r1=0.615m?
(b) with radius r2=1.55m?
(c) with radius r3=2.45m?
I really honestly only need one explained to me, after I see it worked out once, I'm pretty sure I can do it again.

Question

A point charge q1=4.30 nC is located on the x-axis at x=2.30m, and a second point charge q2=-6.00 nC is on the y-axis at y=1.15m.
(a) What is the total electric flux due to these two point charges through a spherical surface centered at the origin and with radius r1=0.615m?
(b) with radius r2=1.55m?
(c) with radius r3=2.45m?
I really honestly only need one explained to me, after I see it worked out once, I'm pretty sure I can do it again.

anonymous · Answer

Okay,I've figured out that a sphere r1 is not affected by these charges because it does not enclose either of them. r2 eencloses only q2, and r3 encloses q1 and q2. Therefore:
(a) Φ =0
(b) Φ= q2/Eo
       =(-6.00*10^-9)/(8.854*10^-12)
       =-677.659 N*m^2/C
(c) Φ= (q1+q2)/Eo
       =[(4.30*10^-9)+(-6.00*10^-9)]/(8.854*10^-12)
       =-192.004 N*m^2/C