Electromagnetic Waves

(a.k.a. What's REALLY In Your Microwave)

What are Electromagnetic (EM) Waves?

Electromagnetic waves are radiation- that is, energy emitted as waves or particles. Radiation is also known as light. Light works by disrupting electric and magnetic fields in the form of a wave. There are many different kinds of EM waves; such as:

  • Radio waves- are used in radios and televisions

  • Infared light- used in night vision goggles and television remotes

  • Ultraviolet light- given off by stars, causes sunburns, detects forged bank notes

  • Visible light spectrum- colors, emitted by the Sun and lightbulbs

  • Microwaves- used to cook food and find out more about nearby galaxies

  • X-rays- used for medical purposes to look at bones and to see through objects

  • Gamma rays- used by doctors to see inside bodies and to kill cancer cells

Where Do Electromagnetic Waves Come From?

Electromagnetic waves are created by vibrating electric energy, producing both electric and magnetic waves. This is where the name 'electromagnetic' waves comes from.

Some examples of things that cause electromagnetic waves are radios, microwaves, and light sources.

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How Does Frequency Affect EM Waves?

There are some electromagnetic waves with extremely long wavelengths-- such as radio waves, for example. These waves require much less energy to make. However, waves with more energy (such as gamma rays) have shorter wavelengths, which produces an unusual side effect.

Electromagnetic waves with an extremely high frequency sometimes make atoms vibrate so fast it flings the electrons off of atoms. This can be extremely damaging to cells and the lifeforms they create. Fortunately, Earth's atmosphere keeps most dangerous EM waves from reaching the surface.

How Are Electromagnetic Waves Different From Mechanical Waves?

Because electromagnetic waves disrupt electric and magnetic fields, they do not require a medium to travel. This means that EM waves can travel in a vaccum (such as space).

Gamma Rays

How Are EM Waves Different from Mechanical Waves?

Mechanical waves need a medium to travel through, whereas electromagnetic waves do not. This means that electromagnetic waves can travel through vacuums such as space.

Electromagnetic waves are also different from mechanical waves in that EM waves are vibrating electric and magnetic fields, while mechanical waves consist of vibrating particles.

Light: Crash Course Astronomy #24