Two long, charged, concentric cylinders have radii of 3.0 and 6.0 cm. The charge per unit length is 4.8 10- 6 C/m on the inner cylinder and -8.0 10-6 C/m on the outer cylinder. Find the electric field at(adsbygoogle = window.adsbygoogle || []).push({});

(a) r = 4.0 cm and

(b) r = 7.1 cm

I know how to find the electric field for each individual cylinder AT 3 and 6 cm... using this equation:

E (electric field) = Q (total charge) / (2*pi*radius*(Q/lambda)*epsilon0)

but i haven't a clue as to how to find the electric field when you include another charged surface using gauss's law...

any help would be much appreciated - as you can see i'm pretty lost.

some equations i know that may or may not help:

Lambda (sp?... linear charge density) = Q / L where Q is the total charge of the surface and L is the length of the gaussian surface

E*A = q/e0 where e0 = 8.85E-12 and q is the charge within the gaussian surface... and A is the surface area of the cylinder (not including the two circles on either end).

thanks

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Gauss's law

**Physics Forums | Science Articles, Homework Help, Discussion**