THE ELECTROMAGNETIC SPECTRUM OF LIGHT

As I have already previously discussed the properties of light, now comes my more favourite part: the electromagnetic spectrum of light. Figure 1 is a diagram of the electromagnetic wavelength of light, it includes various types of light that correspond to different wavelengths. When talking about waves in physics they are classified as a disturbance that travels from one medium to another. This disturbance carries energy, like a fluctuating beam of energy that is oscillating (moving) up and down as it moves forward in direction. The electromagnetic part is the origin of the light itself, consisting of waves composed of oscillating electric and magnetic fields, forming electromagnetic radiation, where the electric and magnetic fields are intertwined and propagate together as a wave. The light that we can see is called visible light, and it includes everything that has colour or shade. Visible light is only a small section of the electromagnetic spectrum though, as there are other more energetic and less energetic forms of light found in the universe. 

(Figure 1. Diagram of the electromagnetic spectrum of light)

Gamma rays have the highest frequency, which means they have the shortest wavelength, this places the light at the most dangerous end of the spectrum. Gamma rays are emitted by the hottest and most energetic celestial objects in the universe, such as neutron stars, supernovae explosions, and black holes. Gamma rays are also emitted by lightning, nuclear explosions, or radioactive materials like uranium. These rays can be used to treat cancer and make very powerful astronomical observations. The reason why they are so dangerous is because of their ability to penetrate deep into the human body, and destroy cellular DNA, which can cause genetic mutations like cancer.

X-Rays are photons, which are atoms that carry light energy, and are caused by changes in the energy of an electron. X-Rays are the next step down from Gamma Rays, their wavelength being a little bit longer. The name X-Ray is well known, as an X-Ray machine does use X-rays to see through the body. X-Rays are less dangerous, they do carry a small risk of cancer but only if in contact with X-Rays for a long period of time. Taking an X-Ray at the hospital won’t cause cancer due to the short amount of time it takes.

Ultraviolet Light or UV has more energy than visible light and is most notably from the sun. UV rays are the type of light that causes sunburn and skin cancer due to the shorter wavelength. Even though human eyes cannot see UV rays, insects like bumblebees can. There are many world wide applications of UV light, for purposes like suntanning, killing bacteria, creating neon lights, medical treatments, and dentistry.

Visible light is exactly as it sounds: visible. Visible Light is what gives colour to everything that the human eye can see. White light is the combination of all visible light, so when refracted through a glass prism, the colours of the rainbow split apart and humans can see them. This happens everyday through different materials that extract colour and emit another colour, like the colour of a banana compared to an apple (this is something I will talk about in a different post). Even though there are millions of different colours that the human eye can detect, visible light is only a very slim section of the electromagnetic spectrum, with the wavelengths being the perfect length to be visible.

Infrared radiation or infrared light is a type of energy that we feel as heat. When sitting next to a warm fire, the warmth is infrared radiation with wavelengths longer than visible light.  Infrared radiation is used in industrial, scientific, military, commercial, and medical applications. Night vision goggles make use of near-infrared light, using specialised heat detectors to create a visual outline. Some animals do this naturally such as snakes, frogs, fish, mosquitos, and bees. Infrared light is what mosquitoes use to find warm blood sources.

Microwave is a form of electromagnetic radiation with wavelengths shorter than other radio waves but longer than infrared waves. Microwaves are most present in deep space, being known as Cosmic Microwave Background Radiation. It is a ‘fossilised’ version of microwave radiation that was emitted seconds after the Big Bang, telescopes and other technological devices are still picking it up. Microwaves are used in various technologies including heating devices like microwave ovens, satellites, TV, telephones, spacecraft communications and radar technology.

Radio waves are self-explanatory, they have the lowest frequency, which means their wavelengths stretch the furthest. Radio waves are used every day in the world, with telecommunication and radio towers transporting information and music. Major cities and small towns make use of radio waves to communicate information and to advertise emergencies. Radio waves are also used in telescopes to make astronomical observations.

This is only a basic overview of the different classifications of light in the electromagnetic spectrum, covering the differences and what we use them for in the modern world. The spectrum is a vital part to the universe, bringing colour, heat, energy, and light. A great place to do more research into a topic like this is the NASA website, or youtube. I also advise to not take my words as your only source of information, please cross reference all information, and leave a comment if you believe something was incorrectly stated. Thank You for taking the time to read this blog, and supporting my adventure into science and maths.