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Resistance on a Wire.

  1. Mar 12, 2009 #1
    I want to know, how do you calculate the resistance of a copper wire with a length of 0.35 meters (1.148 feet) long with a diameter of 0.8118 mm (20 AWG). I found that the resistance of a copper wire in one foot is 98.496 [tex]\omega[\tex] and will be two 1.5V AA battery, so the current running through the wire is going to be approximately 0.031 amps. If If want to connect a switch to the wire, what should be the requirements for the switch or any other electrical devices?

    Here is where I got the resistance for the wire with a 20 AWG gage.
  2. jcsd
  3. Mar 12, 2009 #2
    You could use a volt meter and measure the current coming from the source and the then the current after it has flowed through the wire and calculate the amount of current lost using ohms law I=V/R
  4. Mar 12, 2009 #3


    Staff: Mentor

    Last edited by a moderator: Apr 24, 2017
  5. Mar 13, 2009 #4
    Per the AWG (American Wire Gauge) listed on the HyperPhysics website, 20 gauge solid copper wire @20 C (68 F) has a resistance of 10.15 ohms per 1,000 feet, which equates to .01015 ohms per foot (.01015 ohms/ft * 1,000 feet = 10.15 ohms).

    Per your length of 1.148 feet, that would equate to .0116522 ohms (.01015 ohms/ft * 1.148 feet = .0116522 ohms).
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