Light travels inside a transparent block towards air. The critical angle is 40∘40^\circ40∘. A ray meets the boundary at 35∘ 35^\circ\,35∘ to the surface. Which describes what happens?
the ray is totally internally reflected at 55∘55^\circ55∘ to the normal
the ray is totally internally reflected at 35∘35^\circ35∘ to the normal
the ray is refracted into air at 55∘55^\circ55∘ to the normal
the ray is refracted into air at 35∘35^\circ35∘ to the normal
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.