Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Full-wave rectifier question

  1. Aug 10, 2010 #1
    1. The problem statement, all variables and given/known data

    This circuit has kind of been confusing me. In my notes it says V across capacitor = V - 2V, due to the voltage drop across the 2 diodes per half cycle (assuming that the diodes used have a 1V drop each). But (refering to the attachment with the red line), for the half cycle starting at the top diode, by the time you reach the top of the capacitor, wouldnt the voltage have only travelled through the first diode, thus V across the capacitor = V - 1V?).

    2. Relevant equations

    n/a

    3. The attempt at a solution

    n/a
     

    Attached Files:

  2. jcsd
  3. Aug 10, 2010 #2

    berkeman

    User Avatar

    Staff: Mentor

    You've only highlighted half of the current path. The current flows through 2 diodes in the loop from the source to the storage cap. Which 2 diodes depends on whether the source polarity is positive or negative.
     
  4. Aug 10, 2010 #3

    Zryn

    User Avatar
    Gold Member

    What you are saying would be true if you don't take into account the idea that current will not flow without a closed loop.

    So in order for there to be a closed loop and for current to flow, the second diode in the return path must be turned on.

    Wikipedia has a decent introduction for Diode Bridge, with diagrams.

    http://en.wikipedia.org/wiki/Diode_bridge
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook