Light travels inside glass towards a glass-air boundary. The critical angle is 42∘42^\circ42∘. The ray initially meets the boundary at 55∘ 55^\circ\,55∘ to the surface. Its direction is then changed so that it meets the boundary at 35∘ 35^\circ\,35∘ to the surface. Which describes the ray before and after the change?
before: refraction; after: total internal reflection
before: total internal reflection; after: refraction
before: refraction; after: refraction along the boundary
before: total internal reflection; after: reflection along the boundary
93 exam-style questions on Edexcel GCSE Physics 5.1 Reflection, refraction and lenses, covering 5.1.1 Reflection, refraction and total internal reflection, 5.1.2 Specular and diffuse reflection, 5.1.3 Colour of light: absorption and filters, 5.1.4 Lenses: power, focal length and shape, 5.1.5 Ray diagrams for converging and diverging lenses, and 5.1.6 Real and virtual images. Each one has a worked solution and a mark scheme showing where the marks go.