A very long cylindrical capacitor consists of two thin hollow conducting cylinders with the same axis of symmetry. The inner cylinder has a radius a, the outer one has a radius b. You may ignore end effects.

Question

(a) Fig. 1

(b) Fig. 2

(a) What is the capacitance per unit length? Express your answer in terms of a,band epsilon_0

incorrect



(b) Now consider the limit where b is very close to a . Express b as a+δ ; where δ /a<<1 . What is the capacitance per unit length in that limit? hint: in that limit you can use the following approximation:
ln(1+x)≈ x


Express your answer in terms of a, and δ

Answer 1

Please someone answer.