Learn everything about Current Division in Parallel Circuits.

Current Divider Rule Example # 2: A Difficult CDR Example with Rt 20 ohms given

In this example you'll learn the application of current divider principle to a circuit whose equivalent resistance and one of the two resistors are known.

Statement: A current divider circuit has two resistors with R1 = 30 ohms and R2 is unknown. While the equivalent resistance is 20 ohms. The current flowing through R2 is 2 mA.
By appliying current divider theorem to I1, we obtain.

I1 = (20 ohm/ 30 ohm) * It

or I1 = 0.666 It

From Kirchhoff's Current Law:
It = I1 + I2

It = 0.66 It + I2

0.33 It = I2/

0.33 I= 2 mA

or I= 6 mA

Putting value of Iin I1.
I= 3.99 mA