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-   -   Current Divider rule (http://forum.allaboutcircuits.com/showthread.php?t=78987)

logearav 01-01-2013 05:51 PM

Current Divider rule
 
When it comes to voltage divider, the formula for calculating voltage drop across a particular resistor(Vx) is
(Rx/Total Resistance) * Source Voltage, here Rx is Resistance for which we need to calculate the voltage drop.
But when it comes current divider, the formula is
(Rtotal/Rx) * Itotal.
Why it is not (Rx/Rtotal) * Itotal as in the case of Voltage divider
Revered members,
Could you help in this regard, please?

kubeek 01-01-2013 05:58 PM

How about because it is not a voltage divider but a current divider?
Remeber that current depends on 1/R.. Why donīt you write the eqations and see what you get?

logearav 01-01-2013 06:08 PM

Oh! Thanks a lot kubeek. I am a fool not to realise this basic fact. Once again i thank you wholeheartedly from the bottom of my heart. My teacher too didn't tell this. You have put as simple as that. Wonderful!!!

WBahn 01-02-2013 12:27 AM

You should work out all of the basic formulas that you use from basic concepts. Why do resistors in series add? Why do resistors in parallel add the way they do? Both formulas can be easily derived by applying the constraints imposed by the circuit. Resistors in series have to have the same current and the voltage has to add up across them while resistors in parallel have to have the same voltage and the current has to add up across them. The same for the voltage divider and current divider formulas -- derive them from the basic concepts.

The better you understand where the formulas you use come from, the less likely you are to miremember them or misuse them.


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