Current Divider

The Current Divider

A current divider is two parallel resistors: total current splits between them.

     +---[R1]---+
I →  |          | → I
     +---[R2]---+

The current through R1:

I1 = I_total · R2 / (R1 + R2)

Notice: the other resistor (R2) appears in the numerator.

Why the Opposite Resistor?

Both branches share the same voltage V. By Ohm's law:

• I1 = V / R1
• I2 = V / R2
• I_total = V · (1/R1 + 1/R2) = V · (R1+R2)/(R1·R2)

Solving for I1:

I1 = I_total · R2/(R1+R2)

The lower the resistance in a branch, the more current it takes. The higher-resistance branch appears in the numerator because a larger R2 means R1's branch gets more.

Symmetry

The two always sum to I_total. ✓

Examples

Your Task

Implement double current_divider(double itotal, double r1, double r2) that returns the current through R1.