An IGCSE physics class is carrying out a refraction experiment using a rectangular glass block and optical pins.
Describe how to draw the experimental setup on a page, specifying:
State where the two optical pins, P1 P_1\,P1 and P2P_2P2, should be placed along the line GH\mathbf{GH}GH to trace the ray as accurately as possible.
Even when the experiment is carried out carefully, the results may differ slightly from the theoretical values predicted by Snell's law. Suggest a practical reason for this difference.
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.