# Electromagnetic Waves

## What kind of disturbance creates an electromagnetic (EM) wave?

A vibrating electric charge is the disturbance that leads to the creation of these electromagnetic waves. James Clerk Maxwell discoveries that when magnetic and electric fields combine, they can produce electromagnetic waves. The series of images bellow demonstrates this process in more debt.

## What are two ways that EM waves are different from mechanical waves?

EM waves are unique from mechanical waves in several ways. First of all, they do not require a medium. Due to this capability, they can travel through empty vacuums and space. They can maintain a constant speed in these vacuums, too. On the other hand, mechanical waves do need a medium to transmit through. Another way in which they differ is that mechanical waves are caused by disturbances. Electromagnetic waves are produced by vibration of charged particles and changing mechanical and electric fields, as I explained earlier. These are both two very important types of waves.
Electromagnetic Waves

## What is the electromagnetic spectrum?

The electromagnetic spectrum is the wide range of different wavelengths. Specific radiations occurs in different parts of this spectrum. These unique radiations slightly differ from one another, each posing their own threats and purposes. The following sections are about some different ranges on the spectrum.

## 2. Microwave

I bet that you use a microwave regularly. Most people do. Well, they are possible because of electromagnetic radiation. Microwaves have shorter frequencies than radios and higher frequencies. In fact, the frequency of microwaves ranges from 1GHz to 100GHz. Wavelength wise, microwave wavelengths range from 100 nm to 1 mm. Microwave wavelengths have a higher energy than radio waves but lower than infrared.One use for microwaves is cooking. In this, water molecules absorb certain wavelengths, heating your food to your liking. Unfortunately, the water contained living things also absorb microwave radiation. This can lead to cancer when the cells are damaged by the heat being released. Another use is actually phone calls! Microwave receivers/transmitters can reach out to phones in range from them. Some microwaves even pass through the atmosphere!

## 3. Infrared

Infrared is another form of radiation in the electromagnetic spectrum. It's wavelengths are longer than that of microwaves, spanning from 710 nm - 1 mm. It also has a shorter frequency ranging from about 430 THz down to 300 GHz. It has a higher energy than microwaves but lower than that of visible light. Although you may not realize it, infrared is used in your everyday life quite often. Infrared is perceived as heat to your body and your skin absorbs it. At 37 degrees Celsius, our bodies even give off infrared wavelengths. Night vision googles detect the infrared light emitted by our skin. That's how they work. Toasters utilize infrared to heat up food. So do grills.

## 4. Visible Light

Visible light is the light that we see everyday. The sun's radiation is visible light. Our eyes perceive it as color resulting in the array of colors we see (ROYGBIV). That's one everyday application of visible light. Fireflies, lamps, stars, and so much more also emit visible light. Visible light is everywhere. Visible light has a higher energy than infrared but lower than ultra-violet wavelengths. The frequency of visible light typically ranges from 430 THz to 770 THz. The wavelengths are from 400 nm -700 nm. Individual colors have different wavelengths and frequencies in that vast range. This is the only type of radiation on the electromagnetic spectrum visible by the human eye.

## 5. Ultra-violet

When you tan you are actually absorbing ultra-violet radiation. Ultra-violet is found naturally in the sun. Ultra-violet radiation is invisible and we can't feel its presence but our skin tries to protect itself from absorbing as much of it by darkening, hence the tan you get when you lay out by the pool under the sun. Be careful because ultra-violet can cause cancer in cells. Ultra-violet has a higher energy than visible light but lower than that of an x-ray. Ultra-violet wavelengths span from 10 nm to 310 nm. It has a frequency of about 750 THz to 30 PHz. Ultra violet is used in tanning beds and florescent lights, too. The sun and other young bright stars emit large quantities of it.

## 6. X-ray

Have you ever had an x-ray taken because you broke a bone or a doctor needed to examine you? Well, the common x ray the doctors and dentists use to see your bones is plausible due to x-ray radiation. Airport security also uses x-ray radiation to check you for potential threats before boarding your flight. X-ray has higher energy than ultraviolet but lower than gamma rays. The wavelength is really short and ranges from .01 nm to 10 nm. That is comparable to the size of an atom! The frequency is ranging from roughly 30 PHz to 30 EHz. X-rays can't be seen or felt. They work because they pas through skin and soft tissue but not bone and metal. X-rays can also cause cancer so be cautious about how much you use them.

## 7. Gamma Ray

Finally, gamma rays. Not only do they have the highest energy in the spectrum but they also have the highest frequency and shortest wavelengths. The wavelengths are less than .01 nm. Tat's the size of an atoms nucleus. The frequency is greater than 10 to the 19th power Hz. Their energy is typically more than 100 keV. In terms of practical use, gamma rays can sterilize surgical equipment and try to kill caner cells. Once again, gamma rays can not be seen or heard.