* Refractive Index: The speed of light slows down when it enters a denser medium like glass. This slowdown is measured by the refractive index (n) of the material.
* Different Glasses, Different Refractive Indices: Different types of glass have different compositions, leading to different refractive indices. For example:
* Crown glass (common for lenses): n ≈ 1.52
* Flint glass (used in prisms): n ≈ 1.62
* Some specialized glasses: n can be higher than 2.0
Calculating the Speed of Light in Glass:
1. Speed of Light in Vacuum: The speed of light in a vacuum is a fundamental constant: c ≈ 299,792,458 meters per second.
2. Formula: The speed of light in a medium (v) is calculated by: v = c / n
3. Example: For crown glass (n = 1.52):
* v = 299,792,458 m/s / 1.52 ≈ 197,171,167 m/s
Important Note: The speed of light in glass is always *less* than the speed of light in a vacuum.
