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Magnetic force between two wires

  1. Jul 9, 2015 #1
    I'm wanting to know the force between two wires carrying current but I think I did something wrong when I calculated it. Here is my working.
    I got a value of 0.0021365 ohms for both wires from http://chemandy.com/calculators/round-wire-resistance-calculator.htm
    1000 volts pass through the wires. V=IR so I=V/R which is 1000/0.0021365 = 468055.2305 amps. Is this right?
    Magnetic field strength at distance r, where r = 0.01 is B=μ0I/2πr, which is 4π*10^-7*468055.2305/2π*0.01
    which equals 9.3611046 tesla. is this right?
    Force between the wires is F=BIL where B is 9.3611046 tesla, I is 468055.2305 amps and L equals the length of wire = 0.01 this equals 43815.13971 Newtons. Is this correct? I've checked a few times on my calculator but I still don't believe how large the force is.
  2. jcsd
  3. Jul 10, 2015 #2


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    Staff: Mentor

    I haven't checked your calculations, but the V=IR one is right.

    You might want to consider just how much energy is involved in delivering 400,000+ amps at 1000 V.... How does it compare with the output of a commercial power plant? You should expect to see some big numbers, although in practice your wires would vaporize the moment you turned the power on.
  4. Jul 10, 2015 #3
    Would the wire vaporise at 1000 volts if it where a superconducting wire?
  5. Jul 10, 2015 #4
    If the wire is superconducting then it is not Ohmic and you can't use V = IR.

    In reality, if you were to apply that voltage across a superconducting wire, you'd probably melt the voltage source as that still contributes its own internal resistance to the circuit.
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