Question

You are given kerosene, turpentine and water. In which of these does the light travel fastest ?

Answer 1

It is known that refractive index of a medium, `n = c/v`, where c is speed of light in vacuum and v is speed of light in the medium.
`:. v = c/n`
i.e., light travels fastest in a medium whose refractive index is smallest, i.e., in water,