An optical fibre relies on total internal reflection to transmit light along its length.
To ensure maximum transmission of light (preventing leakage even when the fibre is bent), the critical angle at the boundary must be made as small as possible.
Which statement correctly explains how the refractive index and speed of light in the glass core achieve this condition?
The glass core should have a low refractive index (slowing the light down less) to make the critical angle as small as possible.
The glass core should have a high refractive index (slowing the light down more) to make the critical angle as small as possible.
The glass core should have a low refractive index (slowing the light down less) to make the critical angle as large as possible.
The glass core should have a high refractive index (slowing the light down more) to make the critical angle as large as possible.
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.