Mirage in a box: A classroom activity on the refractive index gradient

The presentation will illustrate how to realize, in a transparent tank, a stable refractive index gradient by using sucrose solutions and a gelling agent. The apparatus will be used in a classroom for hand-on experiments on the refraction of light and on related topics, with particular emphasis on atmospheric effects such as mirages and Fata Morgana. Besides, in the preparation of this activity thermodynamical concepts, such as solubility, phase transitions and thermal stability are also involved. The ingredients and tools used in the preparation are easily available in household stores and do not present any risk of serious injuries. The potential applications of a refractive index gradient for optical fibres will be illustrated as well.