science spectrum

1. The
Electromagnetic
Spectrum

2. Lesson 1: Intro to EM Spectrum
Learning Intentions
By the end of the lesson I will be able to:
• State that the electromagnetic spectrum is a family of waves
• State the order of radiations from longest to shortest
wavelength for the electromagnetic spectrum
• Describe the relationship between frequency , wavelength
and energy for electromagnetic waves
• State the speed that all electromagnetic waves travel at.

3. The Electromagnetic Spectrum

4. The Electromagnetic Spectrum
• The electromagnetic (or EM) spectrum is a
family of waves.
• Electromagnetic waves do not require
particles to travel which means they can travel
in space (a vacuum)
• All Electromagnetic waves travel at the speed
of light: 300,000,000 m/s .

5. The Order of the Spectrum
• The 7 members of the EM spectrum are
arranged in order of wavelength from biggest
to smallest:

6. Remembering the Order
Royal Marines Invade Venus Using X-ray Guns
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Can you think of your own mnemonic?

7. To help you remember…
http://www.youtube.com/watch?v=bj
OGNVH3D4Y

8. Order of the Spectrum
• Since EM radiation travels as a wave, we can
describe it in terms of wavelength (l),
frequency (f) or energy (E).
We know V=f l, if all EM waves travel at
300,000,000 m/s, what is the relationship
between frequency and wavelength?

9. Order of the Spectrum
• As wavelength decreases, frequency and
energy increases and vice versa. So, gamma
has the smallest wavelength but the highest
frequency and energy.
• Which member of the EM spectrum has the
least energy?

10. What do I know?
•Use the following link on a netbook to test you
knowledge!
http://www.wisc-
online.com/objects/ViewObject.aspx?ID=GCH3704

11. Lesson 2&3: EM Spectrum Research
Learning Intentions
By the end of the lesson I will be able to:
• Research and present information to the class
on one member of the electromagnetic
spectrum

12. Revision
• -List all 7 members of the EM spectrum from
lowest to highest frequency
• What speed does all electromagnetic radiation
travel at?

13. Research
• Your task is to research one member of the
electromagnetic spectrum using classroom
and online resources
• You can display your findings any way you
choose; for example power point, a group talk,
poster or even a short film.
It’s up to you!

14. Things to include:
-Uses
-Impact on society
-Potential hazards and methods of protection
-Wavelength and frequency

15. Lesson 4: Radio waves & Microwaves
Learning Intentions
By the end of the lesson I will be able to:
• Describe for radio waves and microwaves:
-Uses
-Frequency and wavelength bands

16. Radio Waves
Velocity in air:
300,000,000 m/s
Wavelength Range:
1mm- 1000m
Frequency:
below 300000000000Hz

17. What are radio waves used for?

18. Uses of Radio Waves
Copy and complete the following spider diagram
for the uses of radio waves
Uses of Radio
Waves

19. Radio Challenge
• Using your mobile phone, computer or other means. Find
out the frequency of 5 popular radio stations and complete
the table below:
Station Frequency Speed Wavelength

20. Radio wave facts
• Radio waves diffract well around obstacles as
they are long wavelength waves
• Radio waves are easily detected using an
aerial and receiver.

21. Microwaves
Velocity in air:
300,000,000 m/s
Wavelength Range:
1mm- 25 μm
Frequency:
3x1011 - 1013 Hz

22. What are microwaves used for?

23. Mobile Phones and Microwaves
Hold the microwave detector beside a ringing
mobile phone.
What do you see?

24. Measuring the speed of light using a
microwave
In wave properties we measured the wavelength of a
microwave using a bar of chocolate. We are going to
repeat the experiment using marshmallows then use our
results to calculate the speed of light in air.
-How will we find the wavelength of the
microwaves?
-What other piece of info do we need to
calculate the speed of the microwaves?
-How will we find the frequency of the
microwaves?
-How does the speed of the microwaves relate to
the speed of light?

25. Microwave facts
• Microwaves are detected by an aerial and
receiver
• Microwaves can be used to heat food, for
satellite communications ( including mobile
phones) and for RADAR.

26. What do I know?
1. State the frequency bands for radio waves and for
microwaves
2. State the wavelength bands for radio waves and for
microwaves
3. Give 2 uses for a) radio waves b) microwaves
4. Name the detector for radio waves and microwaves

27. Lesson 5: Microwaves Research
Learning Intentions
By the end of the lesson I will be able to:
• Research then explain how microwave radiation can
be used to heat food and describe what impact this
has on society.

28. Research Task
Microwave radiation is used to heat food in
restaurants and domestic kitchens. Research the
use of microwaves in heating food and
communicate the advantages and
disadvantages of using microwaves for the
public
Use resources online and in the classroom to
research the above

29. What to include in your notes:
-The physics behind how a microwave heats up food
-How microwaves benefit society
-2 advantages of using a microwave to heat food
-2 disadvantages/ limitations of using microwaves to
heat food (i.e.. can all food be heated this way?)
Useful websites:
http://home.howstuffworks.com/microwave.htm
http://www.universetoday.com/45527/how-do-microwaves-work/
http://www.oprah.com/health/The-Truth-about-Eating-Microwaved-
Food
http://www.livestrong.com/article/548446-disadvantages-with-
cooking-in-the-microwave/

30. Lesson 6: IR, Visible Light & UV
Learning Intentions
By the end of the lesson I will be able to:
• Describe for infra-red, visible light and ultra-violet radiation:
-Uses
-Potential hazards
-Impact on society
-Frequency and wavelength bands

31. Infra-Red (IR)
Velocity in air:
300,000,000 m/s
Wavelength Range:
25um - 750nm
Frequency:
1x1013 - 4x1014 Hz
Also known as
heat

32. Infrared
(Near and Thermal)
• Emitted by
– Sun and stars (Near)
– TV Remote Controls
– Everything at room
temp or above
• Detected by
– Infrared Cameras
– Photodiodes
– (TVs, VCRs)
– (Your skin)

33. Infrared & William Herschel
• Herschel’s Experiment
– Discovered “Invisible Light”
– In 1800, Herschel placed a
thermometer just outside
the red end of the spectrum
– Result: The outside
thermometer registered a
higher temperature

34. Conducting Hershel’s Experiment
• Place a sheet of white paper
inside a cardboard box
• Tape three thermometers
together and place inside box
• Cut a small notch in the top of
the box and position a glass
prism so that the spectrum is
projected inside the box
• Arrange the thermometers so
that one is just outside the red
end of the spectrum, with no
visible light falling on it
What do you
notice about the
thermometers?

35. Focussing IR Radiation
Watch the concave mirror and match demo and try to
explain what happens and why

36. Uses of Infra-red
• Heat to heal
Heat can be used to speed up
the healing process of certain
types of muscle/ tissue
injuries. Infra red lamps are
used to treat the affected area.
• Heat to diagnose
Some tumours give off more
heat than surrounding tissue.
This heat can be detected as
infra red radiation using a
thermo gram, an infra-red
picture.

37. Visible Light
Velocity in air:
300,000,000 m/s
Wavelength Range:
750nm - 400 nm
Frequency:
4x1014 - 7.5x1014 Hz

38. Visible Light
• Emitted by
– The sun and other
astronomical objects
– Laser pointers
– Light bulbs
• Detected by
– Cameras (film or digital)
– Human eyes
– Plants (red light)
– Telescopes

39. “Roy G. Biv”
• The colours of visible light correspond to
different wavelengths of electromagnetic
radiation
• The correct order of the spectrum can be
remembered in different ways
• Richard Of York Gave Battle In Vain

40. Red Sky – Blue Sky
• White light from the sun
is scattered by the earths
atmosphere or a prism
• This results in the sky
being blue and the red
sunrise or sunsets we
see.

41. Ultraviolet (UV)
Velocity in air:
300,000,000 m/s
Wavelength Range:
400nm - 1nm
Frequency:
1 x 1015 – 1 x 1017 Hz

42. Ultraviolet
• Emitted by
– The sun (A)
– Tanning booths (A)
– Black light bulbs (B)
– UV lamps
• Detected by
– Space based UV
detectors
– Phosphorescent paints
– UV Cameras
– Flying insects (flies)

43. Uses of UV Radiation
• Medical Use
U.V. light can be used to
sterilise medical
equipment and treat
some skin conditions like
acne by killing bacteria.
• Police Use
UV light can be used to detect
forged banknotes and stolen
property.
Forensic scientists also use UV
to detect fingerprints, hair
and bodily fluids that would
be invisible to the naked eye

44. Dangers of UV
• Over-exposure to UV radiation can cause skin
damage (like sunburn and premature aging)
which can lead to skin cancer.

45. What do I know?
1. State the frequency bands for IR, visible light and UV.
2. State the wavelength bands IR, visible light and UV.
3. Give 2 uses for a) IR b)UV
4. Name the detector for IR, visible light and UV.

46. Lesson 7: UV Investigation
Learning Intentions
By the end of the lesson I will be able to:
• Describe the hazards associated with UV radiation
• Investigate how sunscreens can minimise risks of UV
radiation

47. Hazards of UV Radiation
• Copy and complete the following spider
diagram for the hazards of UV radiation
Hazards of UV

48. How can you protect yourself from
UV damage?

49. Protecting yourself from UV damage
• Wear a high SPF sunscreen or sunblock
• Stay in the shade when the sun is at its highest
• Cover up in the sun
• Wear sunglasses to protect your eyes
• Use UV beads to monitor sun exposure
• Don’t use sunbeds

50. Testing Sunscreens
We are now going to do an experiment to test
sunscreens using a UV lamp and UV sensitive
beads.
Your teacher will talk you through the
instructions on the experiment guide.

51. Results
Type of Sunscreen Colour of UV beads
Conclusion:

52. UV: True or False?
• Now try the UV true or false cards

53. What do I know?
1.Describe the potential hazards of UV radiation
2. Suggest 2 ways you could protect yourself from
UV radiation

54. Lesson 8: X-rays, gamma rays & revision
Learning Intentions
By the end of the lesson I will be able to:
• Describe for x-rays and gamma rays:
-Uses
-Potential hazards and methods of protection
-Impact on society
-Frequency and wavelength bands

55. X-rays
Velocity in air:
300,000,000 m/s
Wavelength Range:
1nm - 1pm
Frequency:
1x1017 – 1x1020 Hz

56. X-rays
• Emitted by
– Astronomical objects
– X-ray machines
– CAT scan machines
– Older televisions
– Radioactive minerals
– Airport luggage scanners
• Detected by
– Space based X-ray detectors
– X-ray film (photographic film)
– CCD detectors

57. Wilhelm Roentgen
1895
Discovered X-rays
(accidentally)

58. X-Ray of Roentgens Wife’s Hand

59. How X rays work
X rays pass through “light”
atoms such as skin.
X rays are stopped by
“heavy” atoms like bones or
metal.
Photographic film turns
black when hit by X rays

60. Typical Chest X-Ray

61. Normal Broken Arm
Have a look at some
real X-rays

62. Man with 6 nails in his head !!!
he survived !!

63. Sword Swallowing
X-RAY
source
X-RAY film
/ detector

64. X RAY pictures are flat
and don’t show much detail
CAT scanners (Computerised Axial Tomography) use a
beam of x-rays rotating round a patient.
Computers are used to build a 3D image of
the patient

65. CAT scanner

66. CAT scan of a brain
The image
produced by the
CAT scanner is a
“slice through the
patient”
Patient receives a
higher dose of x-
rays

67. X-rays are also used for security
at airports

68. Chandra X-ray Observatory
Chandra X-ray
Observatory
• Chandra is designed to observe
X-rays from high energy
regions of the universe, such as
the remnants of exploded
stars.
• The most sophisticated
observatory built to date.
• Deployed by the Space Shuttle
Columbia on July 23, 1999,

69. Uses of X-rays
Copy and complete the following spider
diagram for the uses of X-rays
Uses of X-rays

70. Hazards of X-rays
• X-rays can change the nature of cells in the
body and over exposure can lead to cancer
developing.
http://www.nhs.uk/conditions/x-
ray/Pages/Risks.aspx
• As a precaution X-rays are not performed on
pregnant women unless deemed clinically
necessary.

71. Gamma-rays
Velocity in air:
300,000,000 m/s
Wavelength Range:
< 1x10-12 m
Frequency:
1x1020 – 1x1024 Hz

72. Gamma Rays
• Emitted by
– Radioactive materials
– Exploding nuclear weapons
– Gamma-ray bursts
– Solar flares
• Detected by
– Gamma detectors and
astronomical satellites
– Medical imaging detectors
(gamma cameras)

73. Uses of Gamma Rays
• Treating cancer (radiotherapy)
• Radioactive tracers:
-Medical: to allow organs in the body to show up on
a scan
-Industrial: to detect cracks in water and gas mains
-Agricultural: to evaluate the benefits of fertilizers
in plants

75. What speed do electromagnetic
waves travel at in air?
340 m/s 300000000 m/s
200000000 m/s 9 m/s

76. All electromagnetic waves are:
Sound waves? Low frequency
waves?
Transverse waves? Longitudinal
waves?

77. What type of electromagnetic wave
is emitted by hot objects?
Infra red X rays
Gamma Visible light

78. What is the lowest frequency wave
in the electromagnetic spectrum?
Gamma Visible light
Micro Radio

79. Which electromagnetic wave is
reflected by the ionosphere?
Microwaves Radio waves
Visible light Ultra violet

80. Visible light
X rays
Which type of EM wave is used for
night vision?
Ultra violet
Infra red

81. Which electromagnetic wave is the
rattlesnake able to detect which human
cannot?
Visible light Infra red
X rays Micro waves

82. Which of the following is not a
property of electromagnetic waves
They can all travel
through a vacuum
They are all
transverse
waves
They all transfer
energy
They can all
penetrate body
tissue

83. Which is the most penetrating wave
in the electromagnetic spectrum?
Gamma
Visible light
X rays
Infra red

84. Which is a type of ionising radiation?
Micro waves Visible light
X rays
Ultra violet rays

85. Which of the following is used for
protection from X rays?
Several cm of lead Thick concrete
Sheet of lead several
mm thick
Metal Grids

86. Which of the following statements is
not true for Gamma rays.
It can kill living
cells
It can penetrate lead
several cm thick
It can be used to
treat cancer
It is safe in low doses

87. Which has the second longest wavelength
in the electromagnetic spectrum?
Gamma rays
Microwaves
X rays Radio waves

88. What type of radiation is visible to
bees?
Ultra violet Infra red
Gamma X rays

89. What were ‘X rays’ initially called
X rays Fracture Rays
High frequency
rays
Unknown Rays