Light

Light, on a scientific level, can be defined by an amount of electromagnetic radiation produced as a photon which is by product of an electron within an atom that having gained additional energy, returns from a higher valance level to it's natural level. These photons have very specific properties, and those observable properties determine the qualitative properties of resulting electromagnetic radiation.

The observable properties of light are not limited solely to that which is visible by the naked eye. Light is recognized as a form of energy, which occurs along a range that is known as the electromagnetic spectrum.

Although it is known that light has a finite speed, light exhibits behavior that of both waves and particles. Until recently it was deemed impossible to detect both the particle nature and the wave nature of light at the same time, as they were believed to be two representations of the same phenomenon. The experiment decided what was observable. This has in recent years been improved and the dual nature of light (wave and particle) has now solidly been proven in combined experiments.

The behaviors of light can generally be classified into five categories:

Particle-like behaviors:

• photoelectric effect

Waveform-like behaviors:

• refraction
• interference
• diffraction
• reflection

In a photoelectric environment, large quantities of photons (which carry a fixed amount of energy) may displace electrons as a result of a collision, producing electric current. As the level of light decreases, there are fewer photons. Electrons can still continue to be displaced, but this will happen at a lower rate.

Refraction occurs when the speed of light is reduced at the point of intersection between light and another medium. The angle of refraction is dependant on the effect of change in the speed of light. A larger reduction in the speed of light within the medium will result in a greater angle of refraction. Diamonds, for example, have a much greater index of refraction than water.

Interference occurs when two or more waveforms of light interact with each other. This phenomenon can be classified into two types: constructive, and destructive.

• Constructive interference is when two or more waveforms come together to form a larger and stronger wave.
  • Example: White light is made up of many different waveforms. By projecting the three colors that our eyes have receptors for (red, blue, and green) in a triad, a white light will be seen at the point of intersection. This is the same reason why on LCD screens all colors are required to function to produce white.
• Destructive interference is when two or more waveforms come together to cancel each other out to make a weaker wave.
  • Example: On a soap bubble, white light is destructed into different observable color 'bands'. The darker colors represent places where light is destructed.

The determination of constructive or destructive is dependent on the color of the light emitted.

Diffraction is the visual appearance of light changing shape in accordance with obstacles in its direct path. When light is projected to a plane that has only a small opening for light to pass through, the location at which light is allowed to continue can be identified as a single point source of light. This single point does not limit the projection to only the shape of the point; rather it is re-emitted in the widest possible scope.

Reflection happens when light is transmitted to a medium, absorbed, and re-emitted with the same amount of energy. Reflection can happen in one of two ways: specular, and scattered. Specular reflection occurs when light is projected onto a smooth surface at a definate angle. Scattered reflection is the reflection of light at various different angles.

Quantum mechanical behavior of light

Light is seen as being quantized, i.e. containing discrete packages of energy as reflected by one particular wavelength emitted. These quantized packages are called photons. Any ray of light contains numerous photons, each has its own energy and therefore wavelength. However, most sources of light will generate photons of various frequencies, an important exception being monochromatic light sources, such as lasers.