You are given kerosene,turpentine,and water. In which of these does the light travel fastest? Use the information given in the table below.

Material medium	Refractive index
Water	$1.33$
Kerosene	$1.44$
Turpentine oil	$1.47$

(WATER) The speed of light in a medium is related to its refractive index $(n_m)$ by the formula:
$n_m = \frac{\text{Speed of light in vacuum (or air)}}{\text{Speed of light in the medium}} = \frac{c}{v}$
From this,the speed of light in the medium $(v)$ is given by:
$v = \frac{c}{n_m}$
This shows that the speed of light $(v)$ is inversely proportional to the refractive index $(n_m)$: $v \propto \frac{1}{n_m}$.
Therefore,light travels fastest in the medium with the lowest refractive index.
Comparing the given refractive indices:
- Water: $1.33$
- Kerosene: $1.44$
- Turpentine oil: $1.47$
Since water has the lowest refractive index $(1.33)$ among the three,light travels fastest in water.