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How to Measure the Resistivity of Composite Materials

At first it may seem daunting to determine the resistivity -- that is, the degree to which a material impedes the flow of electric current -- of a substance whose exact composition is unknown. Fortunately, mechanical aids make it unnecessary to calculate resistivity directly. In fact, determining the resistivity of a material can help you identify its components. If you have a compound whose components you know, measuring resistance offers a way to estimate the ratios between less and more resistant elements.

Things You'll Need

Multimeter

Instructions

- 1
  Insert both probes into the proper sockets if you are using an analogue multimeter. One reads "COM" for common; the other displays the ohm symbol (capital omega). The ohm socket might be the same as the socket for voltage. If you are using a digital multimeter, set the dial to measure ohms.
- 2
  Set the range on your multimeter to the closest approximation possible for your compound. While you will still get a correct reading if your range is too wide, the measurement will be less precise.
- 3
  Zero the analogue multimeter by placing the two loose ends of the probes together. Adjust the zero dial until the meter reads zero ohms. Zeroing is unnecessary with a digital multimeter.
- 4
  Place the two probe ends onto the material some distance apart. Take the reading.
- 5
  Adjust the multimeter to a narrower range closer to that of the reading if you desire a higher degree of precision. Then repeat Step 4.

Nature