Types of Light
Light is a form of energy that defined as the electromagnetic radiation, detected by the eye, but light can also encompass radiation that is not visible to the eye. Light is what helps humans and animals to live and go about their lives. The visible portion of the electromagnetic spectrum includes colors that the human eye can detect, There are different types of light waves on the electromagnetic spectrum, including, but not limited to, visible light, microwaves, X-rays, radio waves, gamma rays, ultraviolet and infrared light.
Light is carried in very small packets or photons, which have waves and particles. A photon is a basic unit of light. Light travels in a wave-like pattern, and the speed of which it travels is known as the speed of light. Light has four basic properties and they are intensity, phase, polarization and frequency or wavelength.The color of an object or surface is dependent upon the wavelength it reflects. The first studies of light were done by the ancient Greeks, who figure out the basic laws of reflection and refraction. It was Sir Isaac Newton who came up with the idea that visible light was measurable in a spectrum.
This type of electromagnetic energy is both naturally and artificially generated. For example, lighting and astronomical objects produce radio waves. Radio waves have the longest wavelengths on the electromagnetic scale and are used to operate AM and FM radio and to operate a television. Radio waves carry little energy, and can travel through the atmosphere, in a straight line and reflect off of clouds or be refracted or diffracted. This type of light can be produced naturally by lightning. Used for navigation and bounces radio waves off of an undetected object to discern its location.
Used in radar and cooking equipment, this type of light has an electromagnetic range between 1 mm and 1 meter. The wavelengths are much smaller than that of radio waves. but longer than those of infrared light. Microwave light is used for transmitting information, as it can pass through clouds, smoke and rain. This kind of light is used in cooking, as the wavelengths are tuned so that they can be absorbed by eater, which in turn quickly heats up food. Microwaves can be harmful at a certain degree; at 109 degree Fahrenheit microwaves can destroy human skin.
The term "infrared" comes from the Latin for "infra," which means below, and refers to the lengths of waves falling below red on the visible light scale. This type of light has a longer wavelength than visible light, but is shorter than that of microwaves. It falls on the shorter end of the visible light spectrum, with wavelengths between 700nm and 1 mm. Infrared light is often used for audio and video remote controls and requires and unobstructed line of transmission between transmitter and receiver. It can explain why a TV remote control will not work if an object is between it and the TV. Infrared is the heat radiation given off by and object. It is visible using night vision lenses, which sense when an object loses heat.
Visible light comes before ultraviolet light on the c spectrum after infrared light. This type of light is subdivided into colors, with red having long wavelengths and violet having short wavelengths. This type of light makes up only a small portion of the spectrum.
Visible light falls under the spectrum between 380 nanometers nm and 760 nm. It is easiest to remember the spectrum of visible light by the memory aid, "ROY G BIV," each of the letters representing a color: R stands for the color red, O stands for the color orange, Y stands for the color yellow, G stands for green, B equals blue, the letter I stands for indigo and V for violet.
This type of light has a shorter wavelength than visible light on the electromagnetic scale and its range is 10nm to 400 nm. Humans cannot see ultraviolet light, but it can be felt on the skin, as it is found in sunlight. Ultraviolet light gets it name because its frequencies are higher than violet light, and comes from the Latin for "ultra," or beyond. Some fluorescent lamps and black lights emit ultraviolet light. Ultraviolet light can be used in sterilization and disinfection. At very high levels, it can damage skin and hair, as well as the Earth's ozone layer.
X-ray or X-radiation is a high frequency light form that falls on the far end of the electromagnetic spectrum, after ultraviolet light, but before gamma rays. This type of light has an extremely short wavelength and is used in medical practice, as machines can produce particles or photons which can pass through the skin, but not through bone. X rays are capable of penetrating most substances, but cannot go through heavy metals. They can also be used to determine the flaws in structures.
On the electromagnetic scale, gamma rays have a high frequency and high energy and a very short wavelength. It is the most energetic light wave found on the spectrum and is released in nuclear reactions. The sun is one source of gamma rays as are stars. This type of light is a very intense and powerful ray and can cause severe damage to humans. Doctors can use gamma rays in small doses to treat cancer cells and tumors.
The highest energy radiations known in the universe are cosmic rays. This type of light has an extremely short wavelength and is found in outer space and originates from particles outside of the Earth's atmosphere, though their origination is not entirely known or understood. Cosmic rays are made of almost entirely of protons, but may also consist of helium. Cosmic rays are not generally considered light, but they may strike and destroy atomic matter in the upper atmosphere, and can affect the radiation at the Earth's surface.