Glass Spheres in Water
Purpose
Demonstrates how refractive index contrast at interfaces determines optical behavior. Dry glass spheres appear opaque due to multiple glass-air reflections; adding water reduces the index mismatch, making the spheres nearly transparent and text beneath them readable.
Figure 1:
Left: dry glass spheres scatter light at many glass-air interfaces, obscuring the letter underneath. Right: adding water reduces the index mismatch, making the spheres nearly transparent and the letter readable.
Figure 2:
Clear marbles over printed text. Left: each dry marble acts as a thick lens, magnifying and inverting the text beneath it. Right: adding water reduces the refractive index contrast and diminishes the lensing effect.
Equipment
- 1