The speed of light can vary depending on the medium it is travelling through. In vacuum, the speed of light is approximately 299,792,458 metres per second, which is often referred to as the "universal" speed of light. However, when light enters a transparent medium, such as glass, water, or air, its speed can be slowed down due to the interaction with the atoms and molecules in the material.
The amount of slowing down depends on the properties of the medium and is characterized by a quantity called the refractive index "n". The refractive index of a material is defined as the ratio of the speed of light in vacuum to the speed of light in the material.
$$n=\frac{c}{v}$$
Where:
n = refractive index
c = speed of light in vacuum (approximately 299,792,458 m/s)
v = speed of light in the material.
So, the statement "Light travels through all transparent media at the same speed" is not accurate as the speed of light varies in different media and is affected by the refractive index.
