Chapter 27, Problem 11A

To determine

The speed of light with which it emerges out from the glass.

Explanation of Solution

Introduction: Light encounter two kind of mediums based on refractive index of material: $\left(1\right)$ optically rarer medium, $\left(2\right)$ optically denser medium. Whenever light travels from rarer medium to denser medium, it bends towards normal and when it leaves denser medium then goes away from the normal. This phenomenon is called refraction of light

When ray of travelling within a single medium its speed remains same throughout that medium. If the ray of light decides to travel from one medium to another or rare medium to denser medium, its speed slows down due to absorption and re-emission phenomenon of photon by an atom in a material. Speed remain slows down with respect to initial speed till the medium is present. But as light comes out from denser medium to rarer medium, its speed gets back to its initial value.

Conclusion: Light speed sets to its initial value (initial speed) as it emerges out from the denser medium