APPLICATIONS OF EM WAVES.ppt

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1. Applications of
Electromagnetic Spectrum

3. Objectives:
a.Citeexamplesofpracticalapplications
ofthedifferentregionsofEMwaves,
suchastheuseofradiowavesin
telecommunications.(S10-FE-Iic-d-48)
b.DiscussthepracticalusesofEMwaves
c.DescribehowEMwavescanbeusedin
dailyactivities.

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

5. •Theytravelasvibrationsin
electricalandmagneticfields.
–Have somemagneticandsome
electricalpropertiestothem.

6. Whenanelectricfieldchanges,sodoesthe
magneticfield.Thechangingmagneticfield
causestheelectricfieldtochange.Whenone
fieldvibrates—sodoestheother.
RESULT-An electromagnetic wave.

7. Electromagnetic waves travel VERY
FAST –around 300,000
kilometres per second (the speed
of light).
At this speed they
can go around the
world 8 times in one
second.

8. ElectromagneticSpectrum—nameforthe
rangeofelectromagneticwaveswhen
placedinorderofincreasingfrequency

9. RADIO WAVES
Have the longest
wavelengths
and lowest
frequencies of
all the
electromagneti
c waves.

10. GlobalPositioningSystems(GPS)measure
thetimeittakesaradiowavetotravelfrom
severalsatellitestothereceiver,determining
thedistancetoeachsatellite.

11. Aradiopicksupradiowavesthroughan
antennaandconvertsittosoundwaves.
–Eachradiostationinanareabroadcastsata
differentfrequency.
•#onradiodialtellsfrequency.

12. •Audio –frequency (AF) signals –patterns
of electric current variations.
•Radio –frequency (RF) –high frequency
radio waves.
•Frequency Modulation –frequency of a
wave that changes to match that of a
signal.

13. MRI
(MAGNETIC RESONACE IMAGING)
Uses Short radio waves with a magnet
to create an image.

14. MICROWAVES
Have the
shortest
wavelengths and
the highest
frequency of
the radio
waves.

15. Used in microwave ovens.
•Wavestransferenergytothewaterinthe
foodcausingthemtovibratewhichinturn
transfersenergyintheformofheattothe
food.
APPLICATIONS OF MICROWAVE

16. RADAR (Radio Detection and Ranging)
•A radar system is
consisting of an
antenna, transmitter
and a receiver.
•Electromagnetic sensor
used for detecting,
locating, tracking, and
recognizing objects of
various kinds at
considerable distances.

17. Terrestrial Communications
•Satellite television and cellphone
communication.

18. INFRARED RAYS
Infrared
Lies beyond the
end of the visible
light it is
emitted by all
objects.

19. Thermogram—apicturethatshowsregionsofdifferent
temperaturesinthebody.Temperaturesarecalculatedby
theamountofinfraredradiationgivenoff.
Therefore people give
off infrared rays.
Heat lamps give off
infrared waves.

20. Blueand greenindicate regions of cooler
temperature.
Redand yellowindicate warmer
temperature

21. Applications of Infrared
1.InfraredPhotographs–providesuseful
detailsofthevegetationoftheEarth’s
surface.

22. Applications of Infrared
2.InfraredScanners–showthe
temperaturevariationofthebody.

23. Applications of Infrared
3.InfraredRemoteControls

24. Applications of Infrared
4.Nightvisiongoggles

25. Applications of Infrared
5.Autofocuscameras

26. VISIBLE LIGHT
Shorter wavelength and higher frequency
than infrared rays.
Electromagnetic waves we can see.
Longest wavelength= red light
Shortest wavelength= violet (purple) light

27. When light enters a
new medium it bends
(refracts). Each
wavelength bends a
different amount
allowing white light to
separate into it’s
various colors
ROYGBIV.

28. ULTRAVIOLET RAYS
Shorter
wavelength and
higher
frequency than
visible light
Carry more
energythan
visible light

29. Some Uses of UV Radiation
•Sunisthemainsourceofultraviolet
radiationbuttherearealsoartificial
sourcesofUVlight.
1.UVlampsareusedbybankstocheckthe
signatureonapassbook.

30. Some Uses of UV Radiation
2.UVradiationisalsousedinsterilizing
waterfromdrinkingfountains.

31. Some Uses of UV Radiation
3.UVradiationinsunlightproduces
VitaminDintheskinandgivesus
tanningeffect.

32. Causes your
skin to
produce
vitamin D
(good for
teeth and
bones)

33. Toomuchcancauseskincancer.Suntanor
sunscreenlotionsserveasfiltersto
protectthebodyfromUVradiation.

34. Used to kill bacteria.
(Sterilization of equipment)

35. X-RAYS
Shorter wavelength
and higher
frequency than UV-
rays
Carry a great
amount of energy
Can penetrate most
matter.

36. X-raysareproducedusingX-raytube.They
areemittedwhenfastmovingelectronshit
ametaltarget.
WilhelmConradRoentgendiscoveredX-rays

37. X –RAY MACHINE

38. X –RAY MACHINE

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

40. Too much exposure can
cause cancer
(lead vest at dentist
protects organs
from unnecessary
exposure)

41. Short Wavelength X-rays
Used by engineersto
check for tiny cracks
in structures.
–The rayspass
throughthecracks
andthecracks
appeardarkonfilm.

42. GAMMA RAYS
Shorter wavelength
and higher
frequency than X-
rays
Carry the greatest
amount of energy
and penetrate the
most.

43. Used to treat cancer cells in the process
called radiotherapy.
Can be very harmful if not used
correctly.

44. The Incredible
Hulk was the
victim of gamma
radiation.

45. Exploding nuclear weapons emit
gamma rays.

46. Brief SUMMARY
A.All electromagnetic wavestravel at the same
speed. (300,000,000 meters/second) in a
vacuum.
B. They all have different wavelengthsand
different frequencies.
–Long wavelength-lowest frequency
–Short wavelengthhighest frequency
–The higher the frequency the higher the
energy.