The resistance of a wire of length `80 cm` and of uniform area of cross-section `0.025 cm^2`, is found to be `1.50` ohm. Calculate the resistivity of the wire.

Explanation

Here, length of the wire, `l = 80 cm`
cross-sectional area of the wire, `A = 0.025 cm^2`
resistance of the wire, `R = 1.50 Omega`
As `R = (rho l)/(A), rho = (RA)/(l) = ((1.50 Omega)(0.025 cm^2))/(80 cm) = 0.000469` ohm cm
Note that the unit of `rho` in this case is ohm cm and not ohm m. This is due to the reason that `l` is in cm and `A` is in `cm^2`, i.e., `rho = ("ohm" xx "cm"^2)/((cm))` = ohm cm.