The Electromagnetic Spectrum

What It Is and How it Helps Us Judge Distances in Space

Copyright 2010. PEER.tamu.eduCopyright 2010. PEER.tamu.edu

The Electromagnetic Spectrum:

Waves found on the Waves found on the electromagnetic electromagnetic spectrumspectrum need NO MEDIUM. They are need NO MEDIUM. They are TRANSVERSE waves that travel through TRANSVERSE waves that travel through EMPTY SPACE!!EMPTY SPACE!!

They travel as VIBRATIONS in ELECTRICAL and They travel as VIBRATIONS in ELECTRICAL and MAGNETIC FIELDSMAGNETIC FIELDS

Speed of electromagnetic wavesSpeed of electromagnetic waves = 300,000,000 = 300,000,000 meters/second (Takes LIGHT 8 minutes to travel meters/second (Takes LIGHT 8 minutes to travel from Sun to Earth at this speed!!)from Sun to Earth at this speed!!)

How the EM Spectrum Helps Us Judge Distances in Space:

Because the Universe is so vast, Because the Universe is so vast, interstellar distances are so great that interstellar distances are so great that the light emitted from other objects in the light emitted from other objects in space can take upwards of millions of space can take upwards of millions of years to reach us!!!years to reach us!!!

So how can we tell just how far away So how can we tell just how far away and object is??????and object is??????

How the EM Spectrum Helps Us Judge Distances in Space:

Distances are measured in Light Distances are measured in Light Years Years 1 light year is how far light 1 light year is how far light travels through space in 1 year.travels through space in 1 year.

Because it takes so long for light to travel through space, the light arriving at us would have actually left the object many years ago.

Looking at a far-away star is like looking back in time!!!

How the EM Spectrum Helps Us Judge Distances in Space:

Electromagnetic radiation is arranged on the spectrum from longest to shortest wavelength, from left to right.

The Longer the wavelength the Lower the frequency

The sHorter the wavelength the Higher the frequency.

Look at the capitol letters, they are there as hints to help remember!! Let’s look at a picture on the next slide

This is one picture of the EM Spectrum. Notice the This is one picture of the EM Spectrum. Notice the Wavelength and Frequency of the Waves. What Wavelength and Frequency of the Waves. What do you see?do you see?

How the EM Spectrum Helps us Judge Distances in Space:

But still, how does this help us see objects in space? Well…

Because different types of radiation waves travel through our atmosphere at different frequencies and wavelengths, scientists can determine where an object is located by the type of radiation wave emitting through our atmosphere!!

How the EM Spectrum Helps us Judge Distances in Space:

So, we use specific types of telescopes and satellites out in space to take pictures of the radiation waves and scientists can then determine what type they are, then judge how many light years away the object is!

Here is another example of the EM Spectrum. Here is another example of the EM Spectrum. This picture gives you real world examples to This picture gives you real world examples to compare the size of the waves to.compare the size of the waves to.

Take A Minute – Check This Out!!

Go to the website below to see an interactive visual of the waves found on the electromagnetic spectrum:

http://www.colorado.edu/physics/2000/waves_particles/index.html

Radio Waves and Microwaves

• Radio waves have the Longest wavelengths and Lowest Frequencies of all the electromagnetic waves.

• A radio picks up radio waves through an antenna and converts it to sound waves.

Microwaves

• Microwaves are a type of radio wave. They have the shortest wavelength and the highest frequency of the radio waves.

• Microwave ovens transfer energy to the water in the food causing them to vibrate which in turn transfers energy in the form of heat to the food.

• Microwaves are also used by cell phones and pagers!

So cool! So cool! Or hot, I Or hot, I should say!!should say!!

Infrared Rays

• Shorter wavelengths and higher frequency than microwaves.

• You can feel the longest ones as warmth on your skin!

• Heat Lamps give off infrared waves and so do living things!!

Pictures called Thermograms show

regions of different body temperatures! This picture

shows the infrared radiation given off by the

elephant.

Visible Light

• This is the light we see by everyday. It has shorter wavelengths and a higher frequency than infrared rays.

• This means it is to the right of infrared waves on the electromagnetic spectrum. Remember Remember RROOYYGGBBIIVV,,

thethe colors of the colors of the rainbow!!rainbow!!

Ultraviolet Rays• These have shorter wavelengths still and an

even higher frequency than visible light.

• They carry more energy than visible light.

• Used to kill bacteria and sterilize equipment!

• Causes skin to produce vitamin D, good for teeth and bones!! But, too much can cause SKIN CANCER!!! USE SUNSCREEN!!!!

• Used to treat jaundice in some newborn babies

X-RAYS

• Shorter wavelength and higher frequency than UV-rays

• Great amounts of energy; can penetrate through most matter!

• Bones and teeth absorb x-rays; that is how we see them in the x-ray picture.

• Too much can cause cancer!!

Gamma Rays• Shortest wavelength and

highest frequency!

• Carry greatest amount of energy and can penetrate through the most matter!!

• Used in radiation treatment to kill cancer cells.

• Very harmful if not used correctly!!!

Using the EM spectrum to view Space!!!

• Animation – View a Galaxy at different wavelengths!

– http://www.classzone.com/books/earth_science/terc/content/visualizations/es2801/es2801page01.cfm

Here is a link with an additional activity to help students understand the different electromagnetic waves:

http://http://school.discoveryeducation.com/school.discoveryeducation.com/lessonplans/activities/lessonplans/activities/electromagneticspectrumelectromagneticspectrum//