A student is investigating the refraction and reflection of light in a transparent rectangular block.
They set up an incident ray which enters the block at an angle of incidence iii to the normal. The incident ray line is extended straight through the block as a reference line EFGEFGEFG. After reflecting off the back surface of the rectangular block, the emergent ray is traced using pins P3P_3P3 and P4P_4P4. The line joining P3P_3P3 and P4P_4P4 is extended to intersect the line EFGEFGEFG at a point HHH. The student measures the smaller angle θ\thetaθ between the line EFGEFGEFG and the extended emergent line.
Explain why the optical pins P1P_1P1 and P2P_2P2 placed on the incident ray line should be separated by a distance of at least 3 cm3\text{ cm}3 cm.
In a first trial, the student uses an angle of incidence i=35∘i = 35^\circi=35∘ and measures θ=71∘\theta = 71^\circθ=71∘. Calculate the difference (θ−2i)(\theta - 2i)(θ−2i).
In a second trial, the student uses an angle of incidence i=45∘i = 45^\circi=45∘ and measures θ=88∘\theta = 88^\circθ=88∘. Calculate the difference (θ−2i)(\theta - 2i)(θ−2i).
Theory suggests that θ=2i\theta = 2iθ=2i. State whether the results from (b) and (c) support this theory, and justify your answer by reference to the experimental results.
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.