This simulation shows the refraction of light (change of direction and speed) when it goes from one medium into another.

Instructions:
- Drag anywhere in the center semi-circle to change the angle of incidence.
- The refractive indices can be changed using the slider bars on the right or...
- Tap in the upper right or bottom right of the screen to display a drop-down window.
- Use the drop window for preset materials (air, water, glass, etc.)
- Use the wavelength slider bar to change the colour.
- If index 1 is higher than index 2, the "critical angle" button will appear to place the incident light at exactly the critical angle.
- "colour deviation" will show slightly different amounts of refraction for different colours.