Circuits
Single resistor
Ohm’s law: V = I·R across one resistor
Build a simple DC circuit with one resistor and measure current, voltage, and power. Verify Ohm's law V = IR with live meter readings and formula substitution.
Ohm's law
A battery drives current through a single resistor. Voltage, current, and resistance are linked by V = I·R.
This is the simplest complete circuit: one source and one load. The resistor voltage and branch current follow Ohm's law directly.
- V = I·R
- P = I·V
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
A 9 V battery drives current through a single resistor. If you use a bigger resistor, does more or less current flow?
Predictions to weigh
- A bigger resistor means less current flows.
- A bigger resistor means more current flows.
- Current doesn't depend on resistance.
Variable roles
What you set:
- Resistance R (Ω)
What you measure:
- Power dissipated P (W)
- Current I (A)
How the investigation runs
- Open the single-resistor preset and press Reset. The battery supplies a fixed 9 V.
- Enable the current readout on the resistor.
- Set the resistor's value for each trial and record the current.
Governing equation
Ohm's Law — V = I·R
The current through a resistor is proportional to the voltage across it and inversely proportional to its resistance: I = V/R. Here V equals the full battery EMF, 9 V.
Electrical Power (from V and R) — P = V²/R
Power dissipated by a resistor can be computed directly from voltage and resistance without needing current: P = V²/R.
What the printable worksheet asks students to work out
- For one trial, compute I = E/R using E = 9 V. Compare to the table.
- Explain why doubling the resistance halves the current, using Ohm's law I = E/R at fixed voltage.
Where this shows up beyond the lab
- Your power column (P = E²/R) shrinks as resistance grows, even though voltage stays fixed. Explain why a bigger resistor draws less power from the same battery.
- What would happen to the current (and the battery) if R were set to nearly 0 Ω? Why do real circuits avoid this 'short circuit' condition?
- 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
- More or less?
- Raise the resistance
- Capture the current
- Open the data
- Explain your evidence
Open the interactive simulation to build the scene, press Play, and explore with live measurements and a guided tutorial.