In a physics laboratory, a student performs a ray-tracing experiment using a semicircular glass block.
State two practical precautions the student must take when placing and viewing optical pins to construct an accurate ray trace.
After tracing the refracted ray emerging from the semicircular block, the student measures the acute angle α\alphaα between the flat boundary surface of the block and the refracted ray to be α=71∘\alpha = 71^\circα=71∘.
Calculate the angle β\betaβ between the refracted ray and the normal to the flat boundary surface.
The angle of incidence at the first boundary was i=20∘i = 20^\circi=20∘. A classmate suggests that, theoretically, the angle β\betaβ should be equal to iii.
State whether the experimental result supports this suggestion, and justify your answer using a quantitative comparison.
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.