About Ray Scale

Ray Scale is a free, interactive ray optics simulator built for physics students — including JEE and NEET aspirants — who want an intuitive, hands-on feel for how light actually behaves. It has two simulators: a reflection simulator for concave, convex and plane mirrors, and a refraction simulator for convex/concave lenses and a glass slab, both running the real optics equations underneath every drag.

How to use it

1
Head to Reflection for mirrors, or Refraction for lenses and a glass slab, and add an element from the toolbar.
2
Click any element to select it — it lights up with a glow. Drag it anywhere along the bench to change its distance from the object.
3
Use the ⧉ button to duplicate an element, or ✕ to delete it — either on the card or right above it on the canvas.
4
Click an element's name to rename it. Type exact numbers into the boxes next to any slider, or just drag.
5
Scroll, pinch, or use the +/– buttons to zoom; drag empty space to pan around, the same way you would in Desmos.
6
Switch units — cm, m, ft, in — at any time. Every number on the page updates together.

What it can do

Live object/image distance, image height, magnification, real-vs-virtual, and upright-vs-inverted — shown right next to each image on the canvas, and again in the sidebar. The refraction simulator adds Snell's-law readouts too: angle of incidence, angle of refraction, lateral shift through a glass slab, critical angle, and apparent thickness when viewing through glass. Add as many elements as you want and compare them side by side.

What's next

A combined lab — mirrors and lenses together in one experiment, so a ray can reflect and refract in the same scene — is the next build.

Who made this

Created by @y66.praveen, with visual identity by @y66.prateek. Built for anyone who wants an intuitive, hands-on feel for how real and virtual images actually form.