Refraction of light and lenses – basic principles
How it works
Refraction of light is the change in direction of a light ray at the boundary between two substances with different refractive indices. If light strikes obliquely from an optically thinner medium into an optically denser medium, it is refracted toward the normal; when passing into an optically thinner medium, it is refracted away from the normal. At perpendicular incidence, the direction does not change. Lenses are optical components that, due to their shape and material, converge or diverge light. There are converging lenses (convex) and diverging lenses (concave). With converging lenses, parallel incident light rays are focused at a real focal point; with diverging lenses, they spread out after the lens, as if they came from a virtual focal point. The focal length depends on the shape and the material of the lens.
Light changes its direction when passing between media with different refractive indices. In an optically denser medium, an obliquely incident ray is refracted toward the normal; in an optically thinner medium, it is refracted away from the normal. Converging lenses focus parallel light at a focal point, diverging lenses make it spread out. The focal length depends on the material and shape of the lens.
An example
What happens to a light ray that enters water obliquely from air?
Try it yourself now
50 Exercises
To the learning unit →Own explanation and own practice exercises by AmyMath. Subject reference framework: Physics. The topic assignment may vary by federal state.