helping hand

Discussion in 'Homework Help' started by djstar, May 11, 2008.

  1. djstar

    Thread Starter Active Member

    Jan 26, 2008
    37
    0
    could some one lease give me a helping hand with this please

    17) A circuit consists of a 0.16μf capacitor connected across a 20V, 1 kHz supply. Also in parallel with the capacitor there is a 1kΩ resistor in series with a 0.18H coil.

    Calculate

    The current drawn from the supply
    The phase angle of this current

    (Use the j operator in your calculation.)
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    Calculate the impedance of the inductor and capacitor at 1KHz (source frequency) and then find the equivalent impedance of the circuit . Then divide the equivalent resistance of the circuit form the voltage to find the current.
     
  3. djstar

    Thread Starter Active Member

    Jan 26, 2008
    37
    0
    thanks for the reply. ive come up with the answer

    X_(c ) = 1/2πfc = X_(c ) = 1/(2×π×1000×0.00000016) = 994.71 ohms


    X_l=2πfl=2 × π ×1000 ×0.18 = 1130.97 ohms


    1/(1/((1130.97+1000))+ 1/994.71) = 678 Ω

    20/678 = 0.029 A

    sorry about the poor formula but its was done in microsoft equation wizard and hasent came out that well on this site. im still stuck with part b and with what the j operator bit means.
     
  4. djstar

    Thread Starter Active Member

    Jan 26, 2008
    37
    0
    just realised i used the wrong formula .its should be 0.02A with the formula

    z= √(R^2+ (Xl-Xc )^2 )
     
  5. Digi Dave

    Member

    Apr 25, 2008
    26
    0
    Z= 691.55678 ohms

    I = 0.02892 amps

    Phase angle 11'degrees leading because capacitor is taking more of the current than the inductor.
    ( tan of X / R . = 136.26/678 )
     
    Last edited: May 11, 2008
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