A student determines the refractive index nnn of a rectangular transparent block using a ray-tracing method with optical pins.
After outlining the block and tracing the path of the light rays, the student measures the following lengths from their drawing:
The refractive index nnn is calculated using the equation:
n=ab n = \frac{a}{b} n=baCalculate the value of the refractive index nnn. Give your answer to an appropriate number of significant figures (2 or 3 s.f.).
The first trial of this experiment was conducted at an angle of incidence i=30∘i = 30^\circi=30∘. Suggest two additional, suitable values for the angle of incidence iii that the student should use to repeat the experiment and improve the reliability of the results.
State two practical precautions that should be taken during this optical pin experiment to ensure accurate measurements.
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.