if you do a dimension testing you are eliminating a very important factor which is resistivity here is how: rho= omega*meter length=meter Area= meter^2 if you put in these values you get R = omega which is correct. eventhough rho is a constant (generally but it can change with temperature) you cannot eliminate it if you do a dimensional comparision so the error is eliminatin rho from the dimensional analysis good job you almost got me there!