Set the multimeter to read resistance by turning its dial to the ohms setting, marked by the Greek letter "omega."
Plug the red probe of the multimeter into the "voltage" socket and the black lead into the "COM" socket.
Touch the leads to each end of the rod and look at the resistance reading. The rod with the lowest reading is the best conductor.
Begin determining the properties of the rods to calculate electrical resistance over a certain length. Get the length and radii of the rods. To calculate the radius of a circle, measure the rods' diameters through the center and halve them. For example, assume you have a 6-foot-long,1-inch-radius copper rod and a 10-foot-long, 1/4-inch-radius silver rod.
Square the radii and multiply them by pi to determine the area. In the example, the copper rod has an area of approximately 3.14 square inches because the square of the radius is 1, and pi can be rounded to 3.14. Calculate the silver rod's area by multiplying: (pi)(1/4)(1/4) = (pi)*1/16, or 0.196 square inches.
Consult an electrical resistivity chart to determine the resistivity of silver and copper in ohms per meter. According to Georgia State University, copper has a resistivity of 1.68*10^-8 ohms/meter, or 0.0000000168. Silver has a resistivity of 1.59*10^-8 ohms/meter, or 0.0000000159.
Substitute the measurements you've learned -- length, area, and resistivity -- into the equation R = rL/A. A website hosted by the University of Virgina states that R equals resistance as a whole, r equals resistivity as an intrinsic property of the metal, L equals length and A equals area. The copper rod has a total resistance of 3.21*10^-8 ohms. The silver rod has a resistance of 8.11*10^-7 ohms. Although silver has a lower intrinsic resistivity than copper, its geometry makes the silver rod less conductive.