Disappearing Beaker

Optics > Refraction > Index of Refraction

DCS# 6A40.30

DISAPPEARING BEAKER

APPARATUS

Pyrex 600 ml beaker	101-01-C
Pyrex 100 ml beaker, no grads	101-01-C
glycerine	202-02-A
video camera	102-09-D

DESCRIPTION

The index of refraction of glycerine is nearly equal to that of Pyrex. When the glycerine is poured into the inner beaker and allowed to overflow into the larger beaker, the immersed part of inner beaker disappears.

NOTES

Glass must be cleaned thoroughly.

Variations:
Rest coin on submerged glass object so it appears to be suspended in the liquid.
Half fill bottle with eyedropper and pass around.

The somewhat larger version (101-01-B), shown at the right, is used for outreach events.

REFERENCES

Sutton, L-33.

TPT 15, 438 (1977).