# Electromagnetic Waves

## What is an Electromagnetic Wave?

An electromagnetic wave is a mechanical wave that does not need a medium to travel. Most traditional waves, such as transverse and longitidunal require a medium.

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

Firstly, electromagnetic waves do not require a medium to travel, where as mechanical waves do. Also a electromagnetic is made of electric and mechanical components, and a mechanical wave is not.

## What type of disturbance creates a EM wave?

An electric vibration creates an electromagnetic wave.
The Electromagnetic Spectrum

## The Electromagnetic Spectrum

Heinrich Hertz discovered radiowaves in the late 1880's.Radiowaves are sent out from radio stations to provide music for all. This is used in car, and personal radios throughout the world.

Wavelength (m) : > 1 x 10-1

Frequency (Hz) : < 3 x 109

Energy (J) : < 2 x 10-24

## Microwave

Microwave ovens are traditionally used in many households, to quickly warm and cook food. The actual microwaves are used to vibrate the molecules of the food, thus cooking it.

Wavelength (m) : 1 x 10-3 - 1 x 10-1

Frequency (Hz) : 3 x 109 - 3 x 1011

Energy (J) : 2 x 10-24- 2 x 10-22

## Infrared

The infrared region of the spectrum allows for the invention of night vision googles. The infrared is picked up by the googles pick up the heat in our skin and appear to the user.

Wavelength (m) : 7 x 10-7 - 1 x 10-3

Frequency (Hz) : 3 x 1011 - 4 x 1014

Energy (J) : 2 x 10-22 - 3 x 10-1

## Visible Light

This portion of the electromagnetic spectrum, called visible light is the light and colors visable to the human eye. Our eyes can only see this small portion of the spectrum. For example rainbows and fireflies are some of the things the human eye is able to see.

Wavelength (m) : 4 x 10-7 - 7 x 10-7

Frequency (Hz) : 4 x 1014 - 7.5 x 1014

Energy (J) : 3 x 10-19 - 5 x 10-19

## Ultra-violet

Ultra-violet energy is given off by the sun and other large stars throught the glaxay. This radiation is the cause of our tans, and also sunburns.

Wavelength (m) : 1 x 10-8 - 4 x 10-7

Frequency (Hz) : 7.5 x 1014 - 3 x 1016

Energy (J): 5 x 10-19 - 2 x 10-17

## X-ray

X-rays are commonly used in doctors offices, dentists, and even by airport secuirty. An x-ray allows for the contents or insides of an object or body to be visable without removing the outer protection.

Wavelength (m) : 1 x 10-11 - 1 x 10-8

Frequency (Hz) : 3 x 1016 - 3 x 1019

Energy (J) : 2 x 10-17 - 2 x 10-14

## Gamma Ray

Gamma rays are created by nuclear reactions and are extremely useful for those in need of cancer treatmnet. Gamma rays are used in chemotherapy to kill the cancer cells. thus making it a very important part of the spectrum.

Wavelength (m) : < 1 x 10-11

Frequency (Hz) : > 3 x 1019

Energy (J) : > 2 x 10-14