current divider rule

Discussion in 'Electronics Resources' started by sadaf, Sep 27, 2010.

  1. sadaf

    Thread Starter New Member

    Aug 4, 2010
    my question is:
    in cdr formula why don't we put the resistance in the numerator of that resistor across which we want to find out the current...

    Ia= (Rt*It)/(Ra)

    or in the special case of CDR

    Ia= (Rb*It)/(Ra+Rb)

    according to me, as current is inversely related with resistance so that's why.....................

    what do you think?give me your thoughts about this........?
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    If you mean Rt=Ra+Rb then clearly you'll get the wrong result. Ia would exceed It - which would be unexpected to say the least!

    Your question isn't clear to me. What is the heart of the problem from your perspective?
  3. Ghar

    Active Member

    Mar 8, 2010
    Current is inversely related with resistance yes, but with current division you have two (or more) resistors in parallel rather than two (or more) resistors in series.

    The branch with 0 resistance would get 100% of the current.
    With a voltage divider if one resistance is 0 that resistance gets 0% of the voltage.

    It's an inverted situation, you swapped voltage and current as well as series and parallel.
  4. sadaf

    Thread Starter New Member

    Aug 4, 2010
    OK i understood......