PETER APRAHAMIAN / SCIENCE PHOTO LIBRARY. PETER APRAHAMIAN / SCIENCE PHOTO LIBRARY.
Assortment of geometry instruments; two pairs of compasses (used for drawing circles), a protractor (centre, for measuring angles), set square and a ruler. When photographed through cross polarised light, coloured patterns are seen on the plastic instruments. These indicate stress patterns, with areas of similar colour representing regions under similar degrees of stress. This phenomenon, known as photoelasticity, is applied in engineering design where a transparent plastic model with loads proportional to a real object may be made to determine stress conditions in the real object.
Model release not required. Property release not required.