optics.gif (6954 bytes)

INVISIBILITY

(This demonstration is no longer done because of Carbon Tetrachloride requirement.)






EQUIPMENT
    redball.gif (326 bytes) Pyrex Beakers
    redball.gif (326 bytes) Carbon Tetrachloride
    redball.gif (326 bytes) Benzene
    redball.gif (326 bytes) Video Camera




NARRATIVE
         A pyrex beaker is shown to the class. When dipped into a tank filled with a clear fluid, it seems to disappear. The fluid is a mixture of 590 cm3 and 410 cm3 benzene (ratio = 1.44:1) and has the same index of refraction as pyrex glass. Light passing through the fluid and the glass is not deviated noticeably, so that the beaker seems to be invisible.