Resistores em série (Rs)

Two resistors in series: sum

With resistors in series the equivalent resistance is just R = R₁ + R₂. The same current runs through both (Kirchhoff's current law), and the source voltage splits in proportion to each resistance: V₁ = I·R₁ and V₂ = I·R₂. The total always ends up larger than either resistor on its own. Take an example: 1 kΩ + 2.2 kΩ = 3.2 kΩ, and at 12 V the current is 3.75 mA, giving V₁ = 3.75 V and V₂ = 8.25 V.

Applications

Think voltage dividers for reference generation or ADC scaling. You also reach for series when you need a non-standard value out of off-the-shelf parts, or in the classic pull-up + sense pairing, where one resistor pulls a line high and another in series reads the current.

FAQ

Why does the same current flow through both? There is only one path, so charge conservation forces the current to be identical at every point of the series loop.

How does voltage divide? Each resistor gets its share: V_i = V_total · R_i / R_total.

Series or parallel for higher precision? Series lets you tune by adding small values, while parallel brings an existing value down without swapping the part out.