How to Determine the Electric Potential Difference in a Coaxial Cable?

[dancer18]

Physics 2 coaxial potential help!

https://wug-s.physics.uiuc.edu/cgi/courses/shell/common/showme.pl?cc/DuPage/phys2112/summer/homework/Ch-22-E-Potential/IE_cylindersV/coax.gif

The diagram above shows a coaxial cable. The inner conductor has radius a = 0.0025 m. The outer conductor is a cylindrical shell with inner radius b = 0.0075 m, and outer radius c = 0.008 m from the center. Both conductors are coaxial. For every length L = 10 m of cable, there is a total charge q = 2.8e-008 C on the inner conductor and a total charge of Q = -5.6e-006 C on the outer conductor.

Determine the electric potential difference between the labeled points A and B.

PLEASE 've been working on this problem for about THREE hours, and I still can't get it! I'm so confused. Please please please!

I tried using the voltage equations from c to b and then adding it w/the voltage from b to a. and it's wrong!

 

[zzzoak]

I think you may find first E for r>=c.
Please use Gauss law.
Integral of E from r=c to infinity will give potential at r=c.
Use the condition that potential at infinity = 0.
Go the same way to the center.