Refraction and Reflection – Ray Diagrams Simulation
Description
A light ray travels down through air and crosses a boundary into a denser medium, bending toward the normal as it does. The simulation draws the incident ray (blue), the refracted ray (its colour matching the chosen medium), and a faint reflected ray (green), with angle arcs marked off a dashed normal line. Pupils drag in the top half of the canvas — or use the slider and arrow keys — to change the angle of incidence, and switch the lower medium between water (n = 1.33, teal), glass (n = 1.50, amber), and diamond (n = 2.42, violet). Live readouts show the angle of incidence θ₁, the angle of refraction θ₂, the refractive indices n₁ → n₂, and the critical angle for the reverse path. It is built on Snell’s law, n₁ sin θ₁ = n₂ sin θ₂, and lets pupils see directly how a higher refractive index bends light more sharply toward the normal. Full ClassAdapt accessibility is built in: light/high-contrast default with a dark navy toggle, Irlen overlays, reading ruler, dyslexia spacing, CVD filters, reduce-motion, and classroom/projector mode.
Search phrases
refraction, angle of refraction, angle of incidence, Snell’s law, refractive index, bending of light, light through glass, light through water, denser medium, optically dense, normal line, critical angle, total internal reflection, optics, waves, AQA GCSE Physics refraction, ray diagram, light rays, speed of light in different media.
Suggested class activity
Set pairs a prediction challenge before they touch the slider. Tell them the ray will enter at a fixed angle of incidence (say 50°) and ask them to rank water, glass, and diamond in order of how much the ray will bend — most to least — and write down their reasoning. Then they test each medium in turn, record θ₂ for all three, and check their ranking. As an extension, challenge them to find the angle of incidence in diamond that produces exactly a 20° angle of refraction, then explain why the same incidence angle in water would refract to a larger angle. This links the visual bending directly to the relative size of n₂ and reinforces that a higher refractive index slows light more and bends it harder toward the normal.