Final answer:
When light hits a solid that it cannot pass through, it is either reflected or absorbed. The absorption occurs when there is an energy step within the material that matches the light's energy. If there are no such energy steps available, the light may be reflected back or pass through if the material is transparent.
Step-by-step explanation:
Interactions of Light with Solid Materials
When light strikes a solid through which it is unable to pass, several interactions can occur. The light wave may be absorbed, reflected, or both. If light is absorbed by the object, the energy from the light wave is converted into another form of energy within the material, such as heat. Absorption happens when there is an energy step in the atoms or molecules of the material that corresponds with the energy of the light wave. However, certain substances, like some plastics, can later re-emit absorbed light as a different form of light, known as phosphorescence.
If light cannot be absorbed because there are no available energy steps in the material's atoms or molecules, it will be either reflected or refracted. Reflection occurs when the light wave bounces off the surface of the material. An example of this can be seen when a light wave hits a mirror, reflecting light back to our eyes. It's important to note, however, that not all reflection involves clear images like a mirror; matte surfaces scatter reflected light in many directions, leading to diffuse reflection.
In cases where the material is transparent, like certain types of glass, light is not absorbed but instead might be transmitted through the material. Transmission denotes the passage of light through a substance without being absorbed. Transparent materials allow visible light to pass through without being absorbed due to the lack of compatible energy steps for the visible light photons, whereas materials with more opacity will block or absorb more light.
Summarizing, when light encounters a solid material that it cannot pass through, it gets either reflected or absorbed, which depends on the material's properties such as its transparency, opacity, and the energy levels of its atoms or molecules.