help with series RL circuit

Discussion in 'Homework Help' started by DCECD, Aug 9, 2010.

  1. DCECD

    Thread Starter New Member

    Aug 9, 2010
    I have got to use a signal generator and oscilloscope to find the inductance of an inductor in a series RL circuit. resistance is the internal resistance of the signal generator (known quantity).
    frequency and source voltage are set by me.
    i dont seem to be able to work out how to find current or any phase angles and without L i cant work out X or Z.
    any help appreciated??
  2. JDT

    Well-Known Member

    Feb 12, 2009
    As you reduce the frequency, the series impedance of the inductor will fall. The impedance will load the signal generator and so the output voltage will also fall. At some frequency the output voltage with the inductance connected will be exactly half of the voltage when nothing is connected.

    At this frequency the impedance of the inductor will equal the signal generator's internal resistance. The impedance of an inductor is:-

    XL = ωL (Ω) where ω = 2∏f

    So, you know the frequency and the impedance. Calculate L.
  3. DCECD

    Thread Starter New Member

    Aug 9, 2010
    thanks a lot