In an ultralowtemperature experiment a collection of sodium

In an ultra-low-temperature experiment, a collection of sodium atoms enter a special state called a Bose-Einstein condensate in which the index of refraction is 1.57 Times 10^7. What is the speed of light in this condensate? m/s

Solution

n = c/v ,where n is refractive index of condensate and c is the speed of light in vacuum and v is the speed of light in the condensate

v=c/n=(3x10⁸m/s) / (1.57x10⁷)= 19.1m/s