Bending Light: Refraction, Reflection & Prism
Aim a laser at water, glass or diamond, see reflection and refraction with angles, or split white light in a prism.
Drag the laser to change the angle. Change the materials and watch the light bend, reflect, or even split into a rainbow in the prism.
About the Bending Light: Refraction, Reflection & Prism
Free bending light: refraction, reflection & prism. Aim a laser at water, glass or diamond, see reflection and refraction with angles, or split white light in a prism. Drag, change the sliders and see the result live. No sign-up, works on phone and computer. Built for physics, the bending light: refraction, reflection & prism runs instantly in your browser: change a setting or drag an object and the result updates at once, so you learn by trying things out rather than only reading about them.
Aim a laser at water, glass or diamond, see reflection and refraction with angles, or split white light in a prism. Use it to explore physics ideas at your own pace, then check what you found against the key ideas further down this page.
How to use the Bending Light: Refraction, Reflection & Prism
- Use the controls to change Top material n₁, Bottom material n₂ / prism, Custom n₂, Laser angle, Light colour. The simulation reacts instantly.
- Pick an option such as Two materials, Prism (rainbow), Air 1.00, Water 1.33 to switch modes or load an example.
- Where you see a glowing handle, object, weight or atom, drag it with your mouse or finger. Everything responds in real time.
- Watch the readouts and graphs update as you experiment, and compare what you see with the key ideas below.
Things to try
- Find the critical angle from glass to air.
- Try diamond and water.
- Switch to the prism and choose white light.
Key ideas you can learn
- Light bends when it enters a new material.
- n₁ sin θ₁ = n₂ sin θ₂ (Snell's law).
- Beyond the critical angle light reflects completely.
- A prism splits white light because each colour bends by a different amount.
Where this is used in the real world
Lenses, fibre optic cables, cameras, diamonds and rainbows all rely on refraction.
Who is this simulation for?
Physics students in middle school, high school and first-year university, teachers who want a quick demonstration for the projector, and anyone revising for exams. It works well for flipped classrooms because students can explore before the lesson.
For teachers: project it on the board, let students predict what will happen, then run it together. For students: change one thing at a time and write down what changes.
Frequently asked questions
What is Snell's law?
It relates the angles of a light ray in two materials to their refractive indices: n₁ sin θ₁ = n₂ sin θ₂.
Why does a prism make a rainbow?
The refractive index depends on wavelength, so violet bends more than red.
Is the Bending Light: Refraction, Reflection & Prism free to use?
Yes. It is completely free, with no signup, no download and no ads inside the simulation. It runs in your web browser.
Does the Bending Light: Refraction, Reflection & Prism work on a phone or tablet?
Yes. It uses touch as well as the mouse, so you can drag objects with your finger. A larger screen makes the controls easier to see.