The Electromagnetic

Spectrum And

“Wavestown”

What is The Electromagnetic

Spectrum ?

Energy from the Sun travels through space as different types of waves known as electromagnetic radiation. The electromagnetic spectrum is the name that scientists give to all the different sizes and types of waves when they want to talk about them as a group.

Long Wavelength = Low Frequency

Short Wavelength = High Frequency

The size of the waves can be as small as a tiny part of an atom all the way up to the size of a mountain. The shorter and smaller the wavelength, the MORE energy it has.

Notice how the shorter dangerous wavelengths (gamma, x-ray UV) and some of the infrared heat are greatly reduce by the Ozone layer within the Stratosphere.

Earth’s Atmosphere Protects Us From Harmful Radiation from the Sun

Radio Waves

•  Radio: yes, this is the same kind of energy that radio stations emit into the air for your radio to capture and turn into your favorite tunes.

•  But radio waves are also emitted by other things: ... such as stars and gases in space.

•  Car radios, cell phones, TVs, CB radios, and walkie talkies all use radio waves!

Microwaves

•  Microwaves: they will cook your popcorn in just a few minutes!

•  Besides microwave ovens and cell phones, other devices using the microwave range include: o  GPS o  WiFi o  Cordless home phones o  Police Traffic Radar o Military radars (e.g. ships, airplanes and satellites - these

ones can put out A LOT of power, and great caution must be taken to keep people away from the antennas because they can and will cook you like a microwave oven if you get too close, like a few feet away.)

Infrared Waves

•  Infrared (IR): we often think of this as being the same thing as 'heat', because it can makes our skin feel warm.

•  Not all infrared waves put out heat. Remote controls often use infrared waves.

•  There are cameras that can pick up infrared energy, many used in the military and in firefighting (helps locate people in smoke filled homes).

•  Scopes on weapons can use infrared (night vision). •  Heat lamps (in restaurants) use infrared to keep our

food warm. •  Telescopes used to study the stars can pick up

infrared energy.

Infrared

•  The image below of the center region of our galaxy was taken by IRAS (in infrared).

•  The hazy, horizontal S-shaped feature that crosses the image is faint heat emitted by dust in the plane of the Solar System.

Visible Spectrum

•  Visible Light: This is the part of the spectrum that our eyes see.

•  Visible radiation is emitted by everything from fireflies to light bulbs to stars ... also by fast-moving particles hitting other particles.

•  How many objects can you think of that release light? I am sure there are hundreds!

Light Spectrum This is the order in which the colors of light

appear according to their frequency and wavelengths. Red has the longest wavelength and violet has the shortest. The order is the same as what we see in a rainbow and can by can be abbreviated as ROY G BV which stands for:

Red, Orange, Yellow, Green, Blue, & Violet

Visible Light

•  Light can be broken down into the colors of visible light with a prism.

Visible Light Spectrum

When white light is bent, such as through a prism, we are able to see the various colors of visible light. Though important to us, visible light makes up a very tiny part of the entire electromagnetic spectrum.

Rainbows

Ultraviolet

•  Ultraviolet: we know that the Sun is a source of ultraviolet (or UV) radiation, because it is the UV rays that cause our skin to burn! This is why the ozone layer is so important to help protect us from getting too much of this type of radiation from the Sun.

•  Stars and other "hot" objects in space emit UV radiation. •  People wear sunglasses to protect their eyes from the

dangerous UV radiation. •  Tanning salons use this same energy in their tanning beds. •  There are ultraviolet lamps that are used to kill bacteria and

sanitize areas. •  We also use large telescopes to study the release of UV

radiation from objects in space.

Skin Damage from UV Radiation

Our Sun’s Harmful Ultraviolet Waves

•  Our Sun emits light at all the different wavelengths in electromagnetic spectrum, but it is ultraviolet waves that are responsible for causing our sunburns.

Picture showing the UV waves coming from the

sun.

Ultraviolet

•  Ultraviolet (UV) light has shorter wavelengths than visible light.

•  Though these waves are invisible to the human eye, some

insects, like bumblebees, can see them!

X-Rays

•  X-Rays: your doctor uses them to look at your bones and your dentist to look at your teeth. Hot gases in the Universe also emit X-rays .

•  We use X-rays to: –  look inside our bodies, –  X-ray machines at airports to look

inside luggage –  X-ray detectors to find x-ray

energy around our atmosphere in in space

–  X-ray telescopes to study the universe

How we use x-rays

Gamma-Rays •  Gamma-rays: radioactive materials can emit gamma-rays. •  When massive stars become supernovae, they release a

tremendous amount of energy in a “gamma ray burst”

•  How we use gamma radiation: •  cancer radiation treatments •  measuring soil density at construction sites •  ensuring the proper fill level for packaged food and drugs •  sterilizing medical equipment in hospitals •  pasteurizing certain foods and spices •  gauging the thickness of metal in steel mills.

Click on the pic

Gamma-rays

•  But the biggest gamma-ray generator of all is the Universe! It makes gamma radiation in all kinds of ways.

The Moon in Gamma-Rays

•  The gamma-ray moon just looks like a round blob - lunar features are not visible. In high-energy gamma rays, the Moon is actually brighter than the quiet Sun. This image was taken by EGRET.

The Electromagnetic Spectrum

Radio

Microwave

Infrared

Ultraviolet

X-ray

Gamma

Red Orange Yellow Green Blue Violet

Visible

Light

The electromagnetic spectrum is just a name that scientists give a bunch of types of radiation when they want to talk about them as a group.

“Wavestown” 1.  Study the picture of the town. 2.  Fill in the Electromagnetic spectrum below the

picture with the different forms of radiation in the proper order.

3.  Color in the light spectrum (ROYGBV). 4.  Identify the forms of radiant energy in the

Wavestown picture by numbering each example according to the type of wave it is. Then write these examples under the proper wavelength in the table.

On the following slide, the antennae on the Taxi is an example of radio waves being used. It is labeled with a 1 to represent radio waves.

Radio (6) Microwave (3) IR (2)

Visible Light (9) UV (3)

X-ray (6) Gamma (1)

1

1

Radio

1

Microwave

2

2

Infrared

3

1, 2, 3, 4,5, 6, 7

Visible Light

4

4

Ultraviolet

5 5

X-Ray

6

Gamma

7

4

4

4

1

4

4

4

4

1

1