A student investigates the refraction of light through a rectangular glass block using the pin-tracing method.
The student draws an incident ray at an angle of incidence i=35∘i = 35^\circi=35∘ to the normal. They place two pins, P1P_1P1 and P2P_2P2, on the incident ray to define its path. Suggest a suitable minimum distance apart for pins P1P_1P1 and P2P_2P2, and explain why placing them too close together would lead to inaccuracies in the ray trace.
The student views the images of P1P_1P1 and P2P_2P2 through the opposite side of the block. They align two more pins, P3P_3P3 and P4P_4P4, with these images. (i) State one precaution, other than pin spacing, that the student should take to ensure an accurate alignment of the pins. (ii) State which part of the pins (tops, middles, or bases) the student should look at when aligning them, and give a reason for your choice.
The student plans to test the suggestion that a certain ratio of measured lengths, representing the refraction index relationships, is constant for all possible values of the angle of incidence iii. List a suitable set of four additional angles of incidence iii that the student could use, and state why this selection of angles is appropriate.
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.