Phase Shifts

Discussion in 'Homework Help' started by extremeads1, Feb 17, 2007.

  1. extremeads1

    Thread Starter Active Member

    Feb 10, 2007
    64
    0
    Hello,
    I have been taught and seen that there is a lead of current in a capacitor by 90degrees and lag of current in a inductor by 90 degrees.
    What is the reason behind the phase shifts in these components !
    pls do let me know fast..........
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Read the E-book on this site - Volume 2, chapters 3 & 4.
     
  3. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
    145
    Essentially its because the current-voltage relationship for capacitors and inductors is of a variable that is dependant on a rate of change of an instantaneous value in the other variable, i.e. for a capacitor i = C(dv/dt) and for an inductor v = L(di/dt); where the derivative expression is the rate of change of an instantaneous value in the other variable.

    For an explanation of the situation for a capacitor see: Volume II - Chapter 4.2

    For an explanation of the situation for an inductor see: Volume II - Chapter 3.2

    Dave
     
  4. Papabravo

    Expert

    Feb 24, 2006
    10,163
    1,796
    That and the following little nuggets
    Code ( (Unknown Language)):
    1.  
    2. d(sin(x))/dx = cos(x)
    3.  
    4. d(cos(x))/dx = -sin(x)
    5.  
    6. so cos(x) = sin(x-90degrees)
    7.  
    8. and -sin(x) = cos(x+90degrees)
    9.  
    Curious how things unfold
     
  5. extremeads1

    Thread Starter Active Member

    Feb 10, 2007
    64
    0
    Thanks ,
    for posting the reply ,now I Understood .
     
Loading...