Two paths, two stories
Series & parallel resistors
Compare equivalent resistance, branch currents, and voltage drops in two-resistor circuits.
Series & parallel resistorsTRY IT YOURSELF
Equivalent R300 Ω
Total current0.04 A
Current R₁0.04 A
Current R₂0.04 A
Teal + amber · follow the changing valuesIdealized physics model
What if you changed…
Try a starting point
Switch from series to parallel without changing the resistors. Compare total current.
See the calculation
Series: R = R₁ + R₂ · Parallel: 1/R = 1/R₁ + 1/R₂
- R = 100 + 200 = 300 Ω.
- Total current = 12/300 = 0.04 A.
- Voltage drops: V₁ = 4 V; V₂ = 8 V.
What this model assumes
Two ideal ohmic resistors, ideal DC source, zero-resistance wires.
Keep an eye on this
Current is shared equally between parallel branches only when their resistances are equal.
Understand the physics ↗A little question. A clearer picture.
Series & parallel resistors: common questions
Wondering about the why? Start here.
Why is parallel resistance smaller?
Parallel branches offer additional paths for current. At the same voltage, the total current rises, so equivalent resistance V/I falls.
Do series resistors each get the full voltage?
No. They share the supply voltage in proportion to their resistances. Their voltage drops add up to the supply.