Light

Light, on a scientific level, can be defined by an amount of electromagnetic radiation given off by an electron within an atom that, having gained energy, returns from a higher valance level to it's natural level. The emission of the excess energy by the return to the lower valence shell produces this electromagnetic radiation. Upon the return to the natural level, a photon is emitted by the electron with very specific properties. Those observable properties determine the qualitative properties of the light.

Although it is known that light has a finite speed, light exhibits behavior that of both waves and particles. Light is seen as being quantified, i.e. containing discrete packages of energy as reflected by one particular wavelength emitted. These quantified packages are called photons. Any ray of light contains numerous photons (most of a variety of energy levels) and therefore wavelength. 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
• reflection
• interference
• diffraction

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. The amount of energy however is not changed.

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. Diamond has 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, and instead of changing the speed of light, merely returns the light at the same angle with the same amount of energy. In this sense, it exhibits the same behaviors as particles.

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.