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8/14/2019 EM WavesT5

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Electromagnetic Waves Transverse waves without a medium! (They can travel through empty space)


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They travel as vibrations in electrical and

magnetic fields.

Have some magnetic and some electrical

properties to them.


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It propagates (moves) through space carrying

energy from one place to another


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4

The Electromagnetic Spectrum


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The electromagnetic spectrum


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Electromagnetic Spectrumname for the range

of electromagnetic waves when placed in order of

increasing frequency

RADIO

WAVES

MICROWAVES

INFRARED

RAYS

VISIBLE LIGHT

ULTRAVIOLET

RAYS

X-RAYS

GAMMA

RAYS


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Electromagneticwaves

c = 3 x 108 m s-1

Transverse

waves

are

with speed in

vacuum

Components

Radio waves

Microwaves

Infra-red

waves .

Light

Ultra-violet

.

X-rays

Gamma rays

Applications

Radio and televisioncommunication

Satellite television andtelephone

Home electrical appliances,

remote controls and intruderalarms

Optical fibres in medical usageand telecommuncation

Sunbeds, fluorescent tubes and

sterilisationMedical use and engineeringapplications

Medical treatment

consist of


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RADIO WAVES

Have the longestwavelengths and

lowest frequenciesof all the

electromagneticwaves.


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A radio picks up radio waves through an

antenna and converts it to sound waves.

Each radio station in an area broadcasts at adifferent frequency.

# on radio dial tells frequency.


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

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

+


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Electromagnetic waves travel VERYFAST around 300,000 kilometres per

second (the speed of light).

At this speed they can go around the

world 8 times in one second.


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Global Positioning Systems (GPS) measure thetime it takes a radio wave to travel from several

satellites to the receiver, determining thedistance to each satellite.


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Radio Waves:Mobile Phones

Mobile phones use microwave energy. We know that

microwaves can cook food can a mobile phone

cause heating?


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MRI

(MAGNETIC RESONACE IMAGING)

Uses Short wave radio waves with a magnetto create an image.


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MICROWAVES

Have the shortest

wavelengths and

the highestfrequency of the

radio waves.


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Used in microwave

ovens. Waves transfer

energy to the water

in the food causingthem to vibrate

which in turn

transfers energy in

the form of heat tothe food.


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RADAR(Radio Detection

and Ranging)

Used to find the speedof an object by sending

out radio waves and

measuring the time it

takes them to return.


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INFRARED RAYS

Infrared= belowred

Shorterwavelength andhigher frequencythan microwaves.


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Too much can cause skin cancer.

Use sun block to protect against (UVrays)


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Causes your

skin to produce

vitamin D(good for teeth

and bones)


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X- RAYS

Shorterwavelength and

higher frequencythan UV-rays

Carry a greatamount of energy

Can penetratemost matter.


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


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Too much exposure can

cause cancer

(lead vest at dentist

protects organs from

unnecessary

exposure)


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Used by engineers

to check for tiny

cracks instructures.

The rays pass

through the cracks

and the cracksappear dark on

film.


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GAMMA RAYS

Shorter wavelength and

higher frequency than X-

rays Carry the greatest

amount of energyand

penetrate the most.


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Used in radiation treatmentto kill

cancer cells.

Can be very harmful if not used

correctly.


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The Incredible

Hulk was the

victim of gamma

radiation.
http://www.qksrv.net/click-291217-10273794?url=http://www.posternow.de/onlineshop/DirectLinks.tpl?lan=1&cod=1&aid=8460


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Exploding

nuclearweapons emit

gamma rays.

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