The speed of light in air is 3.0 × 108 m/s.
The critical angle for light in a transparent glass material surrounded by air is 42∘42^\circ42∘.
What is the speed of light in the glass material?
1.3×108 m/s1.3 \times 10^8\text{ m/s}1.3×108 m/s
2.0×108 m/s2.0 \times 10^8\text{ m/s}2.0×108 m/s
3.0×108 m/s3.0 \times 10^8\text{ m/s}3.0×108 m/s
4.5×108 m/s4.5 \times 10^8\text{ m/s}4.5×108 m/s
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.