Question

Two long coaxial metal cylinders of inner radius \(r_1\) and outer radius \(r_2\) are separated by material of conductivity \(k\). If cylinders are kept at a potential difference of \(V\), the current flows from one to the other in length \(l\) is:

• A. \(\dfrac{2\pi kl}{\log_e\left(\dfrac{r_2}{r_1}\right)}V\)
• B. \(\dfrac{2\pi kV}{\log_e\left(\dfrac{r_2}{r_1}\right)}\)
• C. \(\dfrac{2\pi klV}{r_2}\)
• D. \(\dfrac{2\pi klV}{r_1}\)

Hint:

For radial conduction between coaxial cylinders, resistance contains the logarithmic term \(\ln\left(\frac{r_2}{r_1}\right)\).

Answer 1

The Correct Option is A