Circuits
Series resistors
Same current, split voltage (voltage divider)
Series resistors — interactive Circuits simulation. Same current, split voltage (voltage divider) Free browser-based virtual physics lab with live SI measurements and a guided tutorial.
Series resistors
Resistors in series share the same current but split the supply voltage — a voltage divider.
Charge flows through one path, so every series element carries the same current. Each resistor drops a portion of the total voltage proportional to its resistance.
- I is the same through each resistor
- V_total = V₁ + V₂
Investigation brief
Plan the question before you open the lab
The brief mirrors the prerendered page: driving question, competing predictions, variable roles, governing laws, setup, analysis and extension prompts remain visible and in this order.
Driving question
Two resistors are connected in series (one after another) across a 12 V battery. If you increase the second resistor's value, does the same current still flow through both?
Predictions to weigh
- No — current splits between the two resistors.
- Yes — series components share exactly one current, no matter their individual resistances.
- Current through each resistor is set independently by its own resistance.
Variable roles
What you set:
- Resistor R2 (Ω)
What you measure:
- Total resistance R_total (Ω)
- Current I (A)
How the investigation runs
- Open the series-resistors preset and press Reset. R1 = 100 Ω is fixed; the battery supplies 12 V.
- Enable the current readout on both resistors.
- Set R2's value for each trial and record the (single, shared) circuit current.
Governing equation
Series Resistance — V = I·R
Resistors in series add directly: R_total = R1 + R2 + ... Since only one current path exists, the same current I = E/R_total flows through every component.
What the printable worksheet asks students to work out
- For one trial, compute R_total = R1 + R2, then I = E/R_total using E = 12 V, R1 = 100 Ω. Compare to the table.
- Confirm from the sim that the current reading is identical at R1 and at R2. Explain why series components must share exactly one current (there's nowhere else for charge to go).
Where this shows up beyond the lab
- Since both resistors share the same current, the larger resistor gets the larger share of the 12 V. Explain why V = IR means voltage divides in proportion to resistance in a series circuit.
- Old-style Christmas lights were wired in series: if one bulb burned out, the whole string went dark. Explain why, using what you know about series current.
- AP Physics 2 — Unit 11: Electric Circuits
- AP Physics C: Electricity and Magnetism — Unit 11: Electric Circuits
- IB Physics — B.5 Current and circuits
- General High School Physics — Electricity & DC circuits
- NGSS High School Physics — Electric current and magnetic fields
- Welcome to Series Resistors
- Select the first resistor
- Press Play
- Split voltage
- Open the Properties panel
- You did it!
Open the interactive simulation to build the scene, press Play, and explore with live measurements and a guided tutorial.