Question 1: A hollow cylindrical resistor with an inner radius r1, an outer radius r2, and of length l, is made of a material whose resistivity if p. Show that the resistance of such a wire comes out to be R=\frac{\rho}{2 \pi \ell} \ln \left(\frac{r_{2}}{r_{1}}\right) for a current traveling radially outwards.

Fig: 1

Fig: 2

Fig: 3