KinexiaLEARN PHYSICS

Circuit Puzzle: Pick the Right Resistor

Each puzzle gives you a battery, a bulb rated for a target current, and a box of resistors. Wire in the resistor that makes the bulb glow perfectly: too much current burns it out, too little leaves it dark.

12 V30 ΩI = V/R = 12/30 = 0.400 A — Bulb glows at 0.4–0.6 A
Resistor:

Pick a resistor so the bulb glows — not dim, not burned!

Round 1 / 4Bulbs lit 0

How to play

  1. Read the battery voltage and the bulb's target current.

  2. Compute the needed resistance with R = V/I.

  3. Pick the closest resistor from the parts box.

  4. Press Power on. Correct current lights the bulb green.

  5. Solve 8 puzzles. A burned-out bulb costs you a strike — 3 strikes ends the game.

Scoring

Each solved puzzle scores 100 points. Solving with the exact calculated resistor (not just the closest) earns a 25-point precision bonus.

Levels

Apprentice

Whole-number volts and amps. The resistor you need is always in the box.

Technician

Decimal values; sometimes two resistors must be combined in series.

Engineer

Tight tolerance: the bulb accepts only ±5% of target current. Measure twice.

What physics did you just use?

You just applied Ohm's law, V = IR, the way every electronics designer does: a resistor is chosen to set the current a component receives. LEDs in your phone, dashboard lights in cars, and sensor circuits all use exactly this calculation — pick R = V/I, and the component gets the current it was designed for. Too little current and it underperforms; too much and it burns out.

Key concepts

  • Ohm's law V = IR
  • Series resistance
  • Current limits
  • Power dissipation P = IV