PhysicsGrade 9Electricity

Circuit Studio: Ohm's Law and Power

Build a simple DC circuit, vary voltage and resistance, inspect current and power, and diagnose safe or unsafe operating ranges.

SimulationsLab index
Textbook unitElectric current and simple circuitsMapped by textbook headings when available
Keywordselectric, current, voltage, resistance, ohmMapped to available textbook headings
Practice modeManipulate, measure, explainUse the controls, then read the live evidence

Electricity · Grade 9

Build, measure, and diagnose a DC circuit

Adjust the supply and resistors, compare series and parallel, and watch every meter respond from the same Ohm's Law used in your textbook.

StatusStable
1

Single resistor: set R1 = 6 Ω, voltage = 9 V. Read the current, then verify using Ohm's Law: I = V ÷ R.

2

Series: add R2 = 6 Ω. Does the current halve compared to a single 6 Ω? Record both and compare Req.

3

Parallel: switch to parallel with the same two 6 Ω resistors. Does current double? Find out why Req drops below R1.

PhETCircuit Construction Kit: DC
Full screen ↗
DC9 V
A1.50 A
R16 Ω
Equivalent R6.00 Ω
Total current1.50 A
Total power13.50 W
R1 — V / I9.0 V / 1.50 A
Circuit insight

V = I × R → 9 V = 1.50 A × 6 Ω (✓ verified).

Safety rule

Keep current below 3 A and power below 24 W. The breaker (switch) trips automatically on overload — just like real protective fuses.

Key principle

Series: resistances add (Req = R1 + R2), so current is shared. Parallel: Req = R1·R2/(R1+R2) — always less than either resistor — so total current rises.

Mission

What to prove in this lab

  1. Relate voltage, resistance, current, and power using measured values.
  2. Predict how bulb brightness changes when resistance or supply voltage changes.
  3. Identify overload conditions from current and power readings.