A cylinderical tube of length L has inner radius a and outer radius b. What is the resistance of the tube between its inner and outer surface ? Given that the resistivity of its material is `rho`.

Explanation

(a) `A=pi(b^(2)-a^(2))`
`R=(pl)/(pi(b^(2)-a^(2)))`
(b) `d_(R)=(rhodx)/(2pixl)`
for a section taken at distance x form centre.
`d_(R)=rho/(2pil)(dx)/x`
`rArrR=intdR=rho/(2pil)underset(b)overset(a)int(dx)/x="ln"(b)/(a)`