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Inductors with apparent negative inductive reactance?

  1. Jan 1, 2008 #1
    1. I am currently progressing through my assignment, however I have been given a circuit with 2 values of Z:

    Z1 has a magnitude of 30 and angle of -31.
    Z2 has a real value of -12 and an imaginary number of -36.

    2. When these are both converted to complex number format:

    Z1 = 25.715 - j15.45
    Z2 = -12 - j36

    3. I have checked the question and at no point does it mention components, however from my research and reading, I have found that an impedance with a negative reactance (i.e. imaginary part) indicates a capacitor. My question is: is this a valid assumption to make?

    I know it seems like a daft question, but I wouldn't want to make an assumption that then has a negative impact on my result!

    Many thanks for any help offered!
  2. jcsd
  3. Jan 1, 2008 #2


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    I would imagine that the presence of the negative real part is of more concern (wikipedia has a fairly comprehensive entry on this... well worth a read).

    Generally the negative imaginary part is capacitance which can usually be considered separately due to superposition. However, given the special nature of negative resistance you should consider this more carefully.
  4. Jan 2, 2008 #3
    Many thanks for the help - didn't even register about the negative resistance!
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