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

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# Gauss's law

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