Electromagnetic Spectrum

The electromagnetic spectrum is basically the range of all possible frequencies that exhibit wave-like behavior as it travels, such as light. The electromagnetic spectrum extends from very low frequencies such as modern radio to very high frequencies, such as gamma radiation. The wavelength of modern radio covers thousands of kilometres while the wavelength of gamma radiation is a fraction of an atom.

James Clerk Maxwell was the first person to discover electromagnetic waves. He calculated the speed of electromagnetic waves using the wave equation and found out that the speed of light coincided with the speed he found, thus he concluded that light was an electromagnetic wave as well. Other electromagnetic waves include, in order of lowest frequency to highest frequency: radio frequency, microwave, far infrared, mid-infrared, near infrared, visible radiation (light), ultraviolet light, X-rays and gamma rays.

Visible light, or visible radiation, has a wavelength of between approximately 400 nanometers to 700 nanometers and it can be directly perceived by the human eye. Other wavelengths, such as nearby infrared (longer than 700 nanometers) and ultraviolet (shorter than 400 nanometers), cannot be seen with the naked eye.

Radio waves are used to transmit data or information. It is usually used by antennas, such as the ones on cars or on radios. Microwaves are super high frequency or extremely high frequency.

Microwaves use volumetric heating which transfers energy through the material electromagnetically, unlike the normal heating, thermal heat flux. The benefit of this is that it is a more uniform heating method and it also reduced heating time.

Terahertz radiation is a region of the spectrum between far infrared and microwaves. This range has rarely been studied as it is at the high end of the band. However, scientists hope to apply terahertz radiation in the armed forces, where the high frequency waves may be able incapacitate the enemies’ equipment.

Infrared light has a wavelength longer than that of visible light and it is most commonly used in infrared cameras. Infrared is used in night vision when there is insufficient visible to see. The infrared night vision devices increase in-the-dark visibility without actually using a light source. Infrared radiation can also determine the temperature of objects. Different temperatures display different colours on a infrared camera, an example would be that thermographic image of a dog.

            Ultraviolet light have wavelengths shorter than visible light but longer than X-ray. UV light is very “energetic” and can easily break chemical bonds, making molecules unusually active or ionizing them. Sunburn is a cause of UV radiation. UV radiation causes disruptive effects on skin cells, which could cause skin cancer. The sun emits a large amount of UV radiation, and it could turn the earth into a barren desert; but the Earth’s ozone layer absorbs it before it reaches Earth.

           

            X-rays are also ionizing, but their higher energies can also allow them to interact with matter. As X-rays can pass through most objects, they can be used to “see through” objects, which can be used in medicine.

           

            Lastly, gamma rays are the most energetic photons, having no defined lower limit to their wavelengths. Not many scientists have research on this topic but they are most used to astronomers in the study of high energy objects or regions. Gamma rays are also used for the irrational of food and seed for sterilisation.

            

            In conclusion, I have learnt a lot from this assignment. I learned more about the electromagnetic spectrum and all the frequencies that fall under it. I have also learned more about the different types of light such as visible light and infrared light.