The world is beautiful and full of colors. We are always amazed by the nature when we see a rainbow. However, the lights we can see with eyes accounts for only a small portion of what nature offers us. The lights in nature actually has much more variety than that, and they are affecting our life at every moment, especially since people found them and applied them in modern life widely.

Light Spectrum

Wikipedia has a comprehensive illustration picture for light spectrum (or more scientifically speaking, electromagnetic spectrum)

All the lights in this picture has two properties: Wavelength and Frequency:

• Wavelength: the distance over which the wave’s shape repeats
• Frequency: the number of occurrences of a repeating event per unit of time

We’ll go from the right of this spectrum to check how each of them gets applied in our day to day life.

Gamma ray

Gammy ray has the smallest wavelength. It carries the most energy. They usually come from the stars in universe or radioactive substances.

Medical radiation therapy for cancer is one application of gammy ray.

X-ray

X-ray can be produced by sending a high-energy beam of electons smashing into an atom like copper. Its wavelength is between 0.03 and 3 nanometers. It can go through human bodies and has been used in medical imaging. Because bones are dense and absorb more x-rays than skin does, a x-ray image shows shadows of the bones while the skin appears transparent. X-ray is als being used in security check.

Ultraviolet

Ultraviolet (UV) has a wavelength from 10 nm to 400 nm. It is present in sunlight and constitutes about 10% of the total radiation from the Sun. Overexposure to UV light can lead to skin cancer and harm the eyes.

Because ultraviolet can also chemical reactions and excite fluorescence in materials, minerals will fluoresce at various wavelengths while being irradiated by UV light.

Visible light

Visible light has wavelengths in the range of 380 to 700 nanometers. The longest wavelengths are red and the shortest are violet. Some colors we see everyday like pink and purple are not in this visilbe light spectrum, that’s because they can only be made from a mix of multiple wavelengths.

When different wavelengths of light pass through the prism, they will be deflected by the prism at different angles, producing a spectrum of colors.

Infrared

Infrared (IR) has wavelengths longer than those of visible light. It is generally invisible to the human eye but we can feel as heat.

Infrared Thermometers is one of its applications, because most of the thermal radiation emitted by objects near room temperature is infrared. Similar applications include thermal imaging where infrared cameras are used to “see” the infrared waves emitting from warm objects.

Microwave

Microwaves have wavelengths ranging from one meter to one millimeter. The prefix “micro-“ in its name is meant to suggest a wavelength in the micrometer range.

They’ve been known to be able to heat and cook food. They ares also being used to transmit singles between earth and satellites.

Radio wave

Radio waves have the longest wavelength, ranging from 1 millimeter to 100 kilometers. They are best known for theirs applications in communication technologies, such as television and mobile phones, because they have the ability to pass through atmosphere, and tend to be scattered rather than absorbed by objects.