$48-$ Find an expression for the resistance between the ends of the half$-$ring shown in Figure $25-51.$ The resistivity of the material constituting the half$-$ring is $\backslash (\backslash$rho $\backslash ).$ Hint: Model the half$-$ring as a parallel combination of a large number of thin half$-$rings. Assume the current is uniformly distributed on a cross section of the half$-$ring.

FIGURE $25-51$ Problem $48$