What is the resistivity of a cylindrical material whose
1Cm length has a resistance of 2ohms the diameter of the wire is 0.5mm.
Given: R = 2 ohms, P = ?, L = 0.01m, Dia = 5*10^-4m,
r = 2.5*10^-4 m.
A = pi*r^2 = 3.14*(2.5*10^-4)^2 = 1.96*10^-7 m^2.
R = pL/A
p = RA/ L = 2*1.96*10^-7/1*10^-2 = 3.93*10^-5 ohm-meters.