How to calculate resistance in wire

Written by michele jensen
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How to calculate resistance in wire
A wire's resistance can be directly measured using a multimeter. (Getty Images)

Wire resistance indicates whether a wire is a good conductor or a good insulator. A good conductor allows electricity to flow more easily while a good insulator inhibits the flow of electricity. Wire resistance equals the wire's resistivity multiplied by the cross sectional area of the wire divided by the length of the wire.

Skill level:

Things you need

  • Wire specification sheet
  • Ruler
  • Calculator (optional)

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  1. 1

    Determine cross sectional area using the product specification, or for standard wires, refer to the wire size conversion tools (such as AWG to mm squared) available at the Engineering Toolbox (see Resources).

  2. 2

    Convert cross sectional area to metres squared by multiplying by ten raised to the negative six.

  3. 3

    Measure wire length in metres.

  4. 4

    Determine wire resistivity using product specification or for common materials, refer to Resistivities for common metals at the Department of Electrical and Computer Engineering site of Brigham Young University (see Resources).

  5. 5

    Plug values into appropriate places in formula.

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