Sunday Science: The Electromagnetic Spectrum

The electromagnetic spectrum. Image courtesy of https://mynasadata.larc.nasa.gov/science-practices/electromagnetic-diagram/

Twinkle, twinkle little star, how I wonder what you are? Well, the stars and other celestial objects we "see" are not just emitting visible light, they are also emitting a huge range of wavelengths across something called the electromagnetic spectrum.

What is the electromagnetic spectrum?

The electromagnetic spectrum is a continuous band of energy that's radiated (travels out) of an object. 

Depending on its wavelength (typical values are shown in brackets below), the different portions of the electromagnetic spectrum can be used for very different things:

• Radio waves (1,000m) - TV and radio signals
• Microwaves (0.01m or cm) - Cooking and mobile phones
• Infrared (0.00001m) - Optical fibre communication
• Visible light (0.0000001m) - Seeing
• Ultraviolet (0.00000001m) - Detecting forged bank notes
• X-rays (0.0000000001m) - Medical imaging of bones and tumours
• Gamma radiation (0.000000000001m) - Killing cancer cells

​Which one is the odd one out (for an electromagnetic perspective)? Find out on the Sunday Science Facebook Group.

What is electromagnetic radiation made up of?

Electromagnetic radiation is created when a particle, such as an electron, is accelerated by an electric field and this causes it to move. As the electron moves, it produces oscillating (moving back and forth in a regular rhythm) electric and magnetic fields. 

Electricity and magnetism are not separate entities. Electricity can cause magnetism and vice versa. The electric field and magnetic field contained in electromagnetic radiation travel at right angles to each other in a bundle of light energy called a photon.

The photon is both a particle and wave. It's a confusing concept and it's further discussed in this previous Sunday Science post.

Every photon travels at the same speed (the speed of light) and moves energy from one place to another. In the electromagnetic spectrum, long wavelengths have the lowest energy. So, radio waves have the lowest energy, and gamma rays have the highest.

Extra reading and watching

The range of the electromagnetic spectrum is used in astronomy to detect and investigate some pretty amazing phenomena. This post provides a great introduction to the topic - and I'll be delving into radio astronomy in the near future.

And if you'd like an introduction to the equations behind the electromagnetic spectrum, check out this video:

Want more Sunday Science? I've just started the Sunday Science Facebook Group. If you've got a question about science, want to see more science on your news feed or just want to keep up to date with the latest on the blog, it would be great to welcome you to the group!

What is Sunday Science?

Hello. I’m the freelance writer who gets tech. I have two degrees in Physics and, during my studies, I became increasingly frustrated with the complicated language used to describe some outstanding scientific principles. Language should aid our understanding — in science, it often feels like a barrier.
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So, I want to simplify these science sayings and this blog series “Sunday Science” gives a quick, no-nonsense definition of the complex-sounding scientific terms you often hear, but may not completely understand. 

If there’s a scientific term or topic you’d like me to tackle in my next post, fire an email to [email protected] or leave a comment below. If you want to sign up to our weekly newsletter, click here.