Optics Bench: Focus the Beam
Parallel rays stream in from the left. Place a lens on the bench so the rays converge exactly on the glowing target. Choose the right focal length and the right position — the thin lens equation never lies.
Move the lens so all rays focus ON the target.
How to play
Pick a lens: converging (f = 10, 20, or 30 cm) or diverging.
Drag it to a position on the optical bench.
Watch the live ray diagram update as you move the lens.
Lock in when the rays hit the target. You have 3 locks per puzzle.
Solve 6 puzzles to win.
Scoring
Each focused puzzle scores 100 points. Focusing on the first lock earns a 50-point optics bonus. Wrong locks just cost you the attempt.
Levels
Lab assistant
Target at 2f. Symmetric, forgiving — learn the ray rules.
Optician
Target at arbitrary positions. Use 1/f = 1/do + 1/di.
Lens designer
Two-lens puzzles: the first lens's image becomes the second lens's object.
What physics did you just use?
You just solved the thin lens equation, 1/f = 1/do + 1/di, the way opticians design glasses, cameras, and microscopes. Parallel rays converge at the focal point — that is literally the definition of focal length. Every camera lens is a stack of such calculations, bending rays so the image lands exactly on the sensor.
Key concepts
- Thin lens equation
- Focal point
- Ray diagrams
- Real image formation