Series and Parallel Circuits Interactive Simulation

When resistors are connected in series, their resistances add up (R_t = R₁ + R₂). When connected in parallel, each branch shares the same voltage, giving a total resistance lower than either individual resistor: R_t = (R₁·R₂)/(R₁+R₂). Students can change resistor 1 and resistor 2 and compare what happens. Use it for physics inquiry with Grades 4–5, Middle School, and High School on a projector or student device.

Standards: NGSS 4-PS3-2

• Why adding a resistor in series always raises the total resistance
• Why adding a resistor in parallel always lowers the total resistance
• How switching between series and parallel changes the current dot density
• Reading R_t off the live formula for both topologies

1. 1Predict how changing resistor 1 will affect the total resistance, then test the prediction.
2. 2Use evidence from the live calculation and visual to explain the result.

Questions teachers ask