Final answer:
The index of refraction of a material measures how much the speed of light changes when it enters the material. A material with an index of refraction of 1.5 means that light travels 1.5 times slower in that material compared to a vacuum. The index of refraction is always equal to or greater than one, as the speed of light is always slower in a material than in a vacuum.
Step-by-step explanation:
The index of refraction of a material is a measure of how much the speed of light changes when it enters that material. If the index of refraction of a material is 1.5, it means that light travels 1.5 times slower in that material compared to its speed in a vacuum. This is because light interacts with the atoms and substructures of the material, which slows it down. For example, if the speed of light in a vacuum is 300,000 km/s, then in a material with an index of refraction of 1.5, the speed of light would be 200,000 km/s. It's important to note that the index of refraction is always equal to or greater than one, because the speed of light is always slower in a material than in a vacuum.