Electromagnetic Spectrum No Password

8/3/2019 Electromagnetic Spectrum No Password

1/23

ELECTROMAGNETIC

SPECTRUM

By

Mr.K.Prashanth


2/23

Brief review:

Water and sound waves transfer energy

from one place to another- they require a

medium through which to travel. They are

mechanical waves.

Electric field-region in which charged

particles can be pushed or pulled.


3/23

Nature of Electromagnetic Waves

They are Transverse waves without a medium. (Theycan travel through empty space)

They travel as vibrations in electrical and magneticfields.

Have some magnetic and some electrical properties tothem.

Speed of electromagnetic waves = 300,000,000

meters/second (Takes light 8 minutes to move from thesun to earth {150 million miles} at this speed.)


4/23

When an electric field changes, so does the

magnetic field. The changing magnetic field causes

the electric field to change. When one field

vibratesso does the other.

RESULT-An electromagnetic wave.

Click hereAnimation: Interaction of vibratingcharges
http://www.colorado.edu/physics/2000/waves_particles/wavpart4.htmlhttp://www.colorado.edu/physics/2000/waves_particles/wavpart4.htmlhttp://www.colorado.edu/physics/2000/waves_particles/wavpart4.htmlhttp://www.colorado.edu/physics/2000/waves_particles/wavpart4.html


5/23

Waves or Particles

Electromagnetic radiation has properties of waves but

also can be thought of as a stream of particles. Example: Light

Light as a wave: Light behaves as a transverse wave

which we can filter using polarized lenses.

Light as particles (photons)

When directed at a substance light can knock electronsoff of a substance (Photoelectric effect)


6/23

B. Waves of the Electromagnetic Spectrum Electromagnetic Spectrumname for the range of

electromagnetic waves when placed in order of increasing frequency

Click here(AnimationSize of EMwaves)

RADIO

WAVES

MICROWAVES

INFRARED

RAYS

VISIBLE LIGHT

ULTRAVIOLET

RAYS

X-RAYS

GAMMA

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


7/23

RADIO WAVES

A. Have the longest wavelengths and lowestfrequencies of all the electromagnetic waves.

B. A radio picks up radio waves through an antenna andconverts it to sound waves.

C. Each radio station in an area broadcasts at a differentfrequency. # on radio dial tells frequency.

D. MRI (MAGNETIC RESONACE IMAGING)

Uses Short wave radio waves with a magnet to create animage


8/23

MRI of the Brain


9/23

AM=Amplitude modulationwaves bounce off ionosphere canpick up stations from different cities.

(535kHz-1605kHz= vibrate at 535 to 1605 thousand times/second)

+


10/23

FM=Frequency modulationwaves travel in a straight line &through the ionosphere--lose reception when you travel out of range.

(88MHz-108MHz = vibrate at 88million to 108million times/second)

+


11/23

Bands of Radio/TV/Microwaves


12/23

MICROWAVES

Microwaveshave the shortest wavelengths andthe highest frequency of the radio waves.

Used in microwave ovens.

Waves transfer energy to the water in the food causing themto vibrate which in turn transfers energy in the form of heat to

the food.

Used by cell phones and pagers.

RADAR (Radio Detection and Ranging) Used to find the speed of an object by sending out radio

waves and measuring the time it takes them to return.


13/23

INFRARED RAYS

Infrared= below red Shorter wavelength and higher frequency than

microwaves.

You can feel the longest ones as warmth on your skin

Heat lamps give off infrared waves.

Warm objects give off more heat energy than cool objects.

Thermograma picture that shows regions of different

temperatures in the body. Temperatures are calculated bythe amount of infrared radiation given off. Thereforepeople give off infrared rays.


14/23
http://www.snellinfrared.com/library/_view_msg.asp?refid=19


15/23

VISIBLE LIGHT

Shorter wavelength and higher frequency thaninfrared rays.

Electromagnetic waves we can see.

Longest wavelength= red light Shortest wavelength= violet (purple) light

When light enters a new medium it bends

(refracts). Each wavelength bends a differentamount allowing white light to separate into itsvarious colors ROYGBIV.


16/23


17/23

ULTRAVIOLET RAYS

Shorter wavelength and higher frequency thanvisible light

Carry more energy than visible light

Used to kill bacteria. (Sterilization of equipment) Causes your skin to produce vitamin D (good for

teeth and bones)

Used to treat jaundice ( in some new born babies. Too much can cause skin cancer.

Use sun block to protect against (UV rays)


18/23

X- RAYS

Shorter wavelength and higher frequency than UV-rays Carry a great amount of energy

Can penetrate most matter.

Bones and teethabsorb x-rays. (The light part of an x-ray image indicates a place where the x-ray was absorbed)

Too much exposure can cause cancer

(lead vest at dentist protects organs from unnecessary exposure)

Used by engineers to check for tiny cracks in structures. The rays pass through the cracks and the cracks appear dark on

film.


19/23


20/23

GAMMA RAYS

Shorter wavelength and higher frequency than X-rays

Carry the greatest amount of energy and

penetrate the most. Used in radiation treatment to kill cancer cells.

Can be very harmful if not used correctly.


21/23

Using the EM waves to view the Sun

AnimationView a Galaxy at different wavelengths
http://www.classzone.com/books/earth_science/terc/content/visualizations/es2801/es2801page01.cfmhttp://www.classzone.com/books/earth_science/terc/content/visualizations/es2801/es2801page01.cfm


22/23

Brief SUMMARY

A. All electromagnetic waves travel at thesame speed. (300,000,000 meters/second in avacuum.

B. They all have different wavelength anddifferent frequencies.

Long wavelength-lowest frequency

Short wavelength

highest frequencyThe higher the frequency the higher the energy.


23/23

Electromagnetic Spectrum No Password

Documents

Transcript of Electromagnetic Spectrum No Password