Reference: L66
Category: Light and Waves
Purpose: Demonstrates various photoelastimetric effects.
Description: 1) Araldite specimens: stress between crossed Polaroids. (Hold at 45deg to axes of Polaroids.)
2) Other plastic specimens: hook, etc.
3) Stained glass specimens: a variety of glass blocks, mounted in cork slabs. Place between Polaroids, and rotate analyser.
4) Biot's experiment: long, hollow glass tube, clamped at its midpoint. Place between crossed polaroids, with its axis at 45deg to axis of polaroids. Strong longitudinally chamois leather moistened with alcohol. When the tube vibrates longitudinally (high pitched whistle is heard) flashes of light appear between the crossed Polaroids. Strain, and therefore, light is greatest near the central clamp and zero at the free ends (anti-nodes).
