Reflection and Refraction

Reflection and Refraction
In this topic lets try to examine what is all about Reflection and Refraction.

• Reflection-

Reflection is the returning, or "bouncing" of a wave off of a surface which resists that kind of wave. When it reflects, it always does so at the exact same angle it came in at. If you shine a light directly at a 90 degree angle, it will come directly back at a 90 degree angle. If you shine it 45 degrees to the left, it will exit 45 degrees to the right. The angle at which the light comes in is called the angle of incidence, while the angle at which it exits is called the angle of reflection. This observation is called the scientific law of reflection, which states that the angle of incidence is equal to the angle of reflection. A reflection coming off a smooth surface is sharp, because the waves are allowed to return "intact", without being disturbed. But, if the reflective surface is not a smooth one, what is called diffuse reflection occurs. Because the surface is not smooth, different parts of the light hit the surface in different places at different depths and different times. This results in a mostly blurred image, which is why rough, grainy surfaces do not reflect images well.

• Refraction

Refraction is the change in direction of a wave when it passes into a new substance. The reason the light changes direction or "bends" is because each different substance has it's own effect on the speed of light within itself. Every substance has an optical density, this number, called the substance's index of refraction, is how well light passes through it, the higher the density, the harder time light has moving through it. This number can be determined in two ways, first, the index can be found by taking the ratio of the speed of light in a vacuum (3x106 km/s) and the speed of light in the substance. It can also be found by taking the ratio of the sine of the angle of incidence and the angle of refraction, similar to the angles mentioned above. This equation is called Snell's Law.