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Difference between wirewound resistor and inductor

  1. Dec 5, 2014 #1
    Hi.

    I am looking to understand the difference primarily in construction between a wirewound resistor and an inductor. Both are formed using a coil loop but are clearly behaving differently. Does the coil in a wirewound resistor induce a magnetic field??

    Thanks,

    Mark.
     
  2. jcsd
  3. Dec 5, 2014 #2

    Danger

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    I'm no expert, but I can give you a very basic starting point. A resistor restricts voltage just because it doesn't conduct electricity very well. An inductor creates a magnetic field that impedes current flow. That's not quite exactly how it goes, but it's the best that I have to offer. Someone else will help you shortly.
     
  4. Dec 5, 2014 #3

    sophiecentaur

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    Any wire wound resistor has Resistance and Inductance. So does a wound Inductor. They are usually designed so that the Inductance of a WW Resistor is negligible compared with the Resistance and the Resistance of and Inductor is negligible, compared with its Inductance.
    When dealing with high frequencies or high powers, the parasitic Resistance and Inductances can be very relevant and circuit design needs to take them into account.
    Metal film resistors can be made that have very low inductance and Power Inductors can be made with thick wire and appropriate core material, giving low Resistance.

    Whilst we are at it, those components will also have parasitic Capacitance, which can also be a nuisance.
     
  5. Dec 5, 2014 #4
    There is a difference in construction. To wind a resistor with very low inductance, take your (insulated) resistance wire and double it back on itself, then wind the coil with the doubled wire. The current will flow around the coil in one direction and then back in the opposite direction, and the magnetic fields cancel.
     
  6. Dec 5, 2014 #5

    sophiecentaur

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    Bifilar wound resistors - good point. The ultimate is metal film without the spiral groves that are normally used to get the wanted value. Very expensive but essential when you work at UHF and above.
     
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