Which of the following statements about refraction and reflection of light is correct?
The speed of light in a plastic of refractive index nnn is equal to the speed of light in a vacuum multiplied by nnn.
The angle of incidence of a light ray at an air-plastic boundary is the angle between the ray and the plastic boundary.
The sine of the critical angle ccc at a plastic-air boundary is equal to 1n\frac{1}{n}n1, where nnn is the refractive index of the plastic.
For light passing from air into plastic, the angle of refraction is directly proportional to the angle of incidence.
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.