1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Current Divider Formula if R for element = 0

  1. Nov 2, 2014 #1
    Hi I was wondering say for example you had this simple current divider circuit.
    I was wondering if R1 for example had zero resistance it would have all current dropped over it. However pertaining to the current divider formula.

    ##I_i = Is (R_T / R_i)##

    Thus if R1 = zero the equation is not defined but that also means R2 = RT and the equation would claim all current would be dropped over R2?
  2. jcsd
  3. Nov 3, 2014 #2


    User Avatar

    Staff: Mentor

    If R1 were zero then it would be a wire not a resistor, so in effect the two terminals of the voltage source would be connected directly to one another forming a short circuit. Try building this circuit and either a fuse will blow or something will break, catch on fire, or explode.

    To properly analyze these situations, you have to recognize that zero resistance is an idealization that doesn't exist in the real world. Instead you must use the very small but non-zero resistance that any real wire has. When you do, you will see that the total current is very large while the current across R2 is near zero.
  4. Nov 3, 2014 #3
    Where did you get that formula from? It does not seem to apply here. You should have the sum of the two resistances in the denominator.
  5. Nov 4, 2014 #4
    Yes I just realised sorry. Now It makes sense.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook