A ray of light travels through an optical fibre made of high-density glass. At the boundary with the outer cladding, the angle of incidence of the light ray is greater than the critical angle of the glass. Describe what happens to the ray of light at this boundary.
24 exam-style questions on Edexcel GCSE Physics 5.1 Reflection, refraction and lenses (physics only). Each one has a worked solution and a mark scheme showing where the marks go.