SIMPLIFIED: "10.2: Reflection"

Link to article: https://phys.libretexts.org/Courses/University_of_California_Davis/UCD%3A_Physics_7C_-_General_Physics/10%3A_Optics/10.2%3A_Reflection 

Note: The image above was taken from the original article.

The article linked above is about reflection! You experience reflections all the time. Mirrors are a great example. When you stand in front of a mirror, you will see a reflection of yourself in the mirror. How does this happen? 

When light rays hit a mirror, that same light will hit the mirror then bounce in another direction. The angle that the light rays bounce from the mirror can be calculated using math. The law that can be used is called the Law of Reflection, which states that the angle of incidence is equal to the angle of reflection. The angle of incidence is the angle between the incoming light ray to the mirror and the normal line. The angle of reflection is the corresponding ray of light, and the angle of reflection is always the same angle of incidence relative to the normal line (the normal line is a perpendicular line from the surface of a mirror, refer to the image at the top for an example). 

The reason why angles are involved is because light rays come out of you in all sorts of angles and directions; it is not just one light ray going straight through the mirror and back. The countless light rays from your body ultimately create the reflection in the mirror that you are able to see. 

Light can also refract, which means it bends when hitting another medium. If you want to learn more about refraction, check out the article that I have simplified on refraction on this website; you will also be introduced to Snell’s Law in that article, which also deals with angles.