Current divider calculator

Current divides in inverse proportion to resistance: I₁ = I × R2 ÷ (R1 + R2). One amp through a 100 Ω and a 300 Ω branch gives 0.75 A in the 100 Ω branch and 0.25 A in the 300 Ω one — the lower resistance takes the larger share.

The current divider looks like the voltage divider with the labels swapped, and that swap is exactly where mistakes happen. In a voltage divider the output uses the resistor it is measured across; in a current divider the branch current uses the *opposite* resistor in the numerator. The physical intuition is simple once seen: current takes the easier path, so the smaller resistance carries more. Its most common practical use is a shunt — putting a known low resistance in parallel with a meter movement so that a known fraction of the current bypasses it.