State two advantages of transmitting signals using light pulses in optical fibres rather than electrical signals in copper cables.
An optical fibre has a glass core with a refractive index of 1.55. Calculate the critical angle c c\,c at the boundary between this glass core and the surrounding air.
State the meaning of the term critical angle.
A ray of light travelling inside the glass core strikes the boundary at an angle of incidence of 45∘45^\circ45∘. Explain what happens to this ray.
216 exam-style questions on CIE IGCSE Physics 3.2 Light, covering 3.2.1a Reflection of light, 3.2.1b Images in a plane mirror, 3.2.2 Refraction of light, 3.2.2a Refraction of light, 3.2.2b Total internal reflection, 3.2.2c Refractive index and critical angle, 3.2.2d Optical fibres, 3.2.3a Converging and diverging lenses, 3.2.3b Ray diagrams and the nature of images, 3.2.3c Virtual images and the magnifying glass, 3.2.3d Correcting long-sightedness and short-sightedness, and 3.2.4 Dispersion of light. Each one has a worked solution and a mark scheme showing where the marks go.