Reflection and Refraction
Light is the reason we are able to see anything at all. Light moves as a wave, bouncing and reflecting off objects so we might see them. Without it, we would be in complete darkness. But if light reflects off everything, then why does a mirror look so different than a wall?
When light from the sun hits an object, one of several things can happen. Light can bend and move through the material, which is called refraction. Or, light can bounce off the material, which is called reflection. The reflection of a wave is simply a process by which a wave, whether light, sound, infrared, or radio waves, hits an object and bounces off it. But this reflection looks quite different for a mirror than it does for a wall.
Law of Reflection
When any wave, including light, hits a surface that is opaque, the light will mostly reflect off that surface. The law of reflection tells us how it bounces off that surface. When a wave is moving toward the surface, it's called the 'incident ray.' When it bounces off, it's call the 'reflected ray.' If you were to draw a line perfectly in between the two rays, the law of reflection tells us that the incident angle is equal to the reflected angle.
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When you look in a mirror, what do you see? As long as the mirror is flat, the picture is nice and clear, and at the correct size, all the parts of you are in the right place. This is because of the law of reflection. But does that mean it only applies to mirrored surfaces?
Types of Reflection
Reflection from the surface of a mirror, or any reflection where all the light rays reflect off a surface at the same angle, is called specular reflection. But, in fact, the law of reflection is always true. When you go from a mirrored surface to a regular surface, it isn't the law that changes, but the surface itself.
Take a look at the table on which your computer is sitting. Run your hand across it. Does it feel smooth? Although something might feel smooth to our hands, the surface contains millions of tiny imperfections. Because of those imperfections, a light wave doesn't hit the flat surface we see. Most of the time it hits an imperfection, and those imperfections could be pointed at any angle at all. Therefore, light waves hit different imperfections and bounce off at different reflected angles. This is called diffuse reflection.
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Specular reflection and diffuse reflection are two types of reflection. The more shiny and mirrored a surface, the more specular reflection occurs, and the more dull a surface, the more diffuse reflection occurs.
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