Light travels faster in air than in water
True or false
The correct answer and explanation is:
True. Light travels faster in air than in water. This difference in speed occurs because light interacts with the medium it travels through, and the optical properties of the medium affect its velocity.
In air, the refractive index is approximately 1.0003, which is very close to 1. This means light moves almost at its maximum speed, which is about 299,792 kilometers per second in a vacuum. However, in water, the refractive index is higher, around 1.33. The refractive index is a measure of how much the speed of light is reduced when it enters a medium other than a vacuum. A higher refractive index means the light is slowed down more. In water, light’s speed is reduced to about 225,000 kilometers per second.
The refractive index of a material is determined by the material’s density and its interaction with light. When light enters a denser medium, like water, its velocity decreases, and its direction changes. This phenomenon is called refraction. The greater the refractive index, the slower the speed of light in that medium.
This difference in speed also affects how light bends when it transitions between different materials. In the case of air to water, the light will bend toward the normal (an imaginary line perpendicular to the surface), which is why objects under water appear bent or distorted when viewed from above the surface.
Thus, light travels faster in air than in water due to the lower refractive index of air compared to water, which means it encounters less resistance in air. This principle is crucial in fields like optics and astronomy, where understanding the behavior of light in different media is essential.